Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2017	Feb. 12, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	HUBBELL INCORPORATED
Entity Central Index Key	0000048898
Document Period End Date	Dec. 31, 2017
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock Shares Outstanding (shares)		54,822,923
Entity Well Known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 6,149,647,615

Consolidated Statement of Income - USD ($) $ in Millions	12 Months Ended
Consolidated Statement of Income - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Net sales	$ 3,668.8	$ 3,505.2	$ 3,390.4
Cost of goods sold	2,516.9	2,404.5	2,298.6
Gross profit	1,151.9	1,100.7	1,091.8
Selling & administrative expenses	648.2	622.9	617.2
Operating income	503.7	477.8	474.6
Interest expense	(44.9)	(43.4)	(31.0)
Investment income	0.9	0.5	0.5
Loss on extinguishment of debt	(10.1)	0.0	0.0
Other expense, net	(6.5)	(4.5)	(25.5)
Total other expense	(60.6)	(47.4)	(56.0)
Income before income taxes	443.1	430.4	418.6
Provision for income taxes	193.2	132.6	136.5
Net income	249.9	297.8	282.1
Less: Net income attributable to noncontrolling interest	6.8	4.8	4.8
NET INCOME ATTRIBUTABLE TO HUBBELL	$ 243.1	$ 293.0	$ 277.3
Earnings per share
Basic (USD per share)	$ 4.42	$ 5.26	$ 4.79
Diluted (USD per share)	$ 4.39	$ 5.24	$ 4.77

Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 249.9	$ 297.8	$ 282.1
Other comprehensive income (loss):
Foreign currency translation adjustments	28.9	(35.4)	(45.5)
Pension and post retirement benefit plans’ service costs and net actuarial (losses) gains, net of taxes of ($1.0), $18.9 and $10.7	4.0	(40.3)	(15.5)
Unrealized gain (loss) on investments, net of taxes of ($0.2), $0.1 and $0.2	0.6	(1.2)	(0.3)
Unrealized gains (losses) on cash flow hedges, net of taxes of $0.4, $0.5 and ($0.3)	(0.8)	(1.4)	1.4
Other comprehensive income (loss)	32.7	(78.3)	(59.9)
Comprehensive income	282.6	219.5	222.2
Less: Comprehensive income attributable to noncontrolling interest	6.8	4.8	4.8
COMPREHENSIVE INCOME ATTRIBUTABLE TO HUBBELL	$ 275.8	$ 214.7	$ 217.4

Consolidated Statement of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Parenthetical Disclosures [Abstract]
Adjustment to pension and other benefit plans tax impact	$ (1.0)	$ 18.9	$ 10.7
Unrealized gain (loss) on investment tax impact	(0.2)	0.1	0.2
Unrealized gain or loss on cash flow hedge tax impact	$ 0.4	$ 0.5	$ (0.3)

Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current Assets
Cash and cash equivalents	$ 375.0	$ 437.6
Short-term investments	14.5	11.2
Accounts receivable, net	540.3	530.0
Inventories, net	634.7	532.4
Other current assets	39.6	40.1
Total Current Assets	1,604.1	1,551.3
Property, Plant, and Equipment, net	458.3	439.8
Other Assets
Investments	57.7	56.4
Goodwill	1,089.0	991.0
Intangible assets, net	460.4	431.5
Prepaid pensions (included in Other long-term assets)	51.1	55.0
TOTAL ASSETS	3,720.6	3,525.0
Current Liabilities
Short-term debt	68.1	3.2
Accounts payable	326.5	291.6
Accrued salaries, wages and employee benefits	76.6	82.8
Accrued insurance	60.0	55.8
Other accrued liabilities	174.9	156.2
Total Current Liabilities	706.1	589.6
Long-term Debt	987.1	990.5
Other Non-Current Liabilities	379.5	341.7
TOTAL LIABILITIES	2,072.7	1,921.8
Commitments and Contingencies (see Note 14)
Hubbell Shareholders’ Equity
Common Stock - Authorized 200,000,000 shares, outstanding 54,882,154 and 55,532,307 shares	0.6	0.6
Additional paid-in capital	11.0	15.4
Retained earnings	1,892.4	1,879.3
Accumulated other comprehensive loss	(269.8)	(302.5)
Total Hubbell Shareholders’ Equity	1,634.2	1,592.8
Noncontrolling interest	13.7	10.4
TOTAL EQUITY	1,647.9	1,603.2
TOTAL LIABILITIES AND EQUITY	$ 3,720.6	$ 3,525.0

Consolidated Balance Sheet (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Common stock, par value (USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized (shares)	200,000,000	200,000,000
Common stock, shares, outstanding (shares)	54,882,154	55,532,307

Consolidated Statement of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows from Operating Activities
Net income	$ 249.9	$ 297.8	$ 282.1
Adjustments to reconcile net income to net cash provided by operating activities, net of acquisitions:
Depreciation and amortization	99.8	92.3	85.2
Deferred income taxes	(14.3)	12.7	(4.5)
Stock-based compensation	22.3	22.3	17.0
Loss on extinguishment of debt	(10.1)	0.0	0.0
(Gain) loss on sale of assets	(11.6)	(5.8)	0.5
Changes in assets and liabilities, net of acquisitions:
Decrease (increase) in accounts receivable	3.9	(42.3)	1.9
Decrease (increase) in inventories	(90.3)	18.4	(80.8)
Increase in current liabilities	57.4	13.8	46.6
Changes in other assets and liabilities, net	50.7	8.4	6.1
Contributions to qualified defined benefit pension plans	(1.7)	(18.0)	(22.6)
Other, net	2.8	11.4	7.9
NET CASH PROVIDED BY OPERATING ACTIVITIES	379.0	411.0	339.4
Cash Flows from Investing Activities
Capital expenditures	(79.7)	(67.2)	(77.1)
Acquisitions, net of cash acquired	(184.1)	(173.4)	(163.4)
Purchases of available-for-sale investments	(20.9)	(20.0)	(24.5)
Proceeds from sales of available-for-sale investments	17.4	13.3	13.8
Proceeds from disposition of assets	18.4	10.8	0.7
Other, net	3.3	6.3	0.9
NET CASH USED IN INVESTING ACTIVITIES	(245.6)	(230.2)	(249.6)
Cash Flows from Financing Activities
Issuance of long-term debt	297.6	397.0	0.0
Extinguishment of long-term debt	(300.0)	0.0	0.0
Issuance of short-term debt	66.3	1.2	48.8
Payment of short-term debt	(1.7)	(51.5)	(2.0)
Make whole payment for extinguishment of long-term debt	(9.9)	0.0	0.0
Debt issuance cost	(3.0)	(3.6)	0.0
Payment of dividends	(157.6)	(144.0)	(133.7)
Payment of dividends to noncontrolling interest	(3.5)	(2.8)	(5.0)
Acquisition of common shares	(92.5)	(246.8)	(79.1)
Payments for share reclassification	0.0	0.0	(200.7)
Other	(10.0)	(8.9)	(7.3)
NET CASH USED IN FINANCING ACTIVITIES	(214.3)	(59.4)	(379.0)
Effect of foreign currency exchange rate changes on cash and cash equivalents	18.3	(27.3)	(21.2)
Increase in cash and cash equivalents	(62.6)	94.1	(310.4)
Cash and cash equivalents, beginning of year	437.6	343.5	653.9
Cash and cash equivalents, end of year	$ 375.0	$ 437.6	$ 343.5

Consolidated Statement of Changes in Equity - USD ($)
$ in Millions

Total

Common Stock

Class A Common Stock

Common Stock

Class B Common Stock

Additional Paid-in Capital

Retained Earnings

Accumulated Other Comprehensive Income (Loss)

Total Hubbell Shareholders' Equity

Non- controlling interest

Beginning of period at Dec. 31, 2014

$ 0.1

$ 0.5

$ 146.7

$ 1,944.1

$ (164.3)

$ 1,927.1

$ 8.6

Increase (Decrease) in Stockholders' Equity [Roll Forward]

Net income

$ 282.1

277.3

4.8

Other comprehensive (loss) income

(59.9)

Stock-based compensation

16.3

Income tax windfall from stock-based awards, net

0.9

Acquisition/surrender of common shares

92.6

Cash dividends declared

(133.8)

Dividends to noncontrolling interest

(5.0)

Director's deferred compensation

6.8

Share reclassification

$ 0.6

(0.1)

(0.5)

(201.5)

End of period at Dec. 31, 2015

0.6

0.0

78.1

1,886.1

(224.2)

1,740.6

8.4

Increase (Decrease) in Stockholders' Equity [Roll Forward]

Net income

297.8

293.0

4.8

Other comprehensive (loss) income

(78.3)

Stock-based compensation

22.5

Income tax windfall from stock-based awards, net

4.8

Acquisition/surrender of common shares

^[1]

90.4

155.5

245.9

Cash dividends declared

(144.3)

Dividends to noncontrolling interest

(2.8)

Director's deferred compensation

0.4

End of period at Dec. 31, 2016

1,603.2

0.6

0.0

15.4

1,879.3

(302.5)

1,592.8

10.4

Increase (Decrease) in Stockholders' Equity [Roll Forward]

Net income

249.9

243.1

6.8

Other comprehensive (loss) income

32.7

Stock-based compensation

22.3

Acquisition/surrender of common shares

^[1]

27.2

72.1

99.3

Cash dividends declared

(157.9)

Dividends to noncontrolling interest

3.5

Director's deferred compensation

0.5

End of period at Dec. 31, 2017

$ 1,647.9

$ 0.6

$ 0.0

$ 11.0

$ 1,892.4

$ (269.8)

$ 1,634.2

$ 13.7

[1]

For accounting purposes, the Company treats repurchased shares as constructively retired when acquired and accordingly charges the purchase price against Common Stock par value, Additional paid-in capital, to the extent available, and Retained earnings. The change in Retained earnings of $72.1 million and $155.5 million in 2017 and 2016, respectively, reflects this accounting treatment.

Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Significant Accounting Policies

Basis of Presentation

The accompanying consolidated financial statements of the Company have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”).

Principles of Consolidation

The Consolidated Financial Statements include all wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated. The Company participates in two joint ventures, one of which is accounted for using the equity method, the other has been consolidated in accordance with the consolidation accounting guidance. An analysis is performed to determine which reporting entity, if any, has a controlling financial interest in a variable interest entity (“VIE”) with a primarily qualitative analysis. The qualitative analysis is based on identifying the party that has both the power to direct the activities that most significantly impact the VIE’s economic performance (the “power criterion”) and the obligation to absorb losses from or the right to receive benefits of the VIE that could potentially be significant to the VIE (the “losses/benefit criterion”). The party that meets both these criteria is deemed to have a controlling financial interest. The party with the controlling financial interest is considered to be the primary beneficiary and as a result is required to consolidate the VIE. The Company has a 50% interest in a joint venture in Hong Kong, established as Hubbell Asia Limited (“HAL”). The principal objective of HAL is to manage the operations of its wholly-owned manufacturing company in China. Under the accounting guidance, the Company is the primary beneficiary of HAL and as a result consolidates HAL. This determination is based on the fact that HAL’s sole business purpose is to manufacture product exclusively for the Company (the power criterion) and the Company is financially responsible for ensuring HAL maintains a fixed operating margin (the losses/benefit criterion). The consolidation of HAL is not material to the Company’s consolidated financial statements.

Use of Estimates

The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts in the Consolidated Financial Statements and accompanying Notes to Consolidated Financial Statements. Actual results could differ from the estimates that are used.

Revenue Recognition

The Company recognizes revenue when persuasive evidence of an arrangement exists, delivery has occurred, the price is fixed and determinable and collection is probable. Product is considered delivered to the customer once it has been shipped and title and risk of loss have been transferred. The majority of the Company’s revenue is recognized at the time of shipment. The Company recognizes less than one percent of total annual consolidated net revenue from post shipment obligations and service contracts, primarily within the Electrical segment. Revenue is recognized under these contracts when the service is completed and all conditions of sale have been met. In addition, within the Electrical segment, certain businesses sell large and complex equipment which requires construction and assembly and occasionally has long lead times. It is customary in these businesses to require a portion of the selling price to be paid in advance of construction. These payments are treated as deferred revenue and are classified in Other accrued liabilities in the Consolidated Balance Sheet. Once the equipment is shipped to the customer and meets the revenue recognition criteria, the deferred revenue is recognized in the Consolidated Statement of Income.

Further, certain of our businesses provide for sales discounts and allowances based on sales volumes, specific programs and customer deductions, as is customary in the electrical products industry. These items primarily relate to sales volume incentives, special pricing allowances, and returned goods. Sales volume incentives represent rebates with specific sales volume targets for specific customers. Certain distributors qualify for price rebates by subsequently reselling the Company’s products into select channels of end users. Following a distributor’s sale of an eligible product, the distributor submits a claim for a price rebate. Customers also have a right to return goods under certain circumstances which are reasonably estimable by affected businesses. Customer returns have historically ranged from 1%-2% of gross sales. These arrangements require us to estimate at the time of sale the amounts that should not be recorded as revenue as these amounts are not expected to be collected from customers. The Company principally relies on historical experience, specific customer agreements and anticipated future trends to estimate these amounts at the time of shipment.

Shipping and Handling Fees and Costs

The Company records shipping and handling costs as part of Cost of goods sold in the Consolidated Statement of Income. Any amounts billed to customers for reimbursement of shipping and handling are included in Net sales in the Consolidated Statement of Income.

Foreign Currency Translation

The assets and liabilities of international subsidiaries are translated to U.S. dollars at exchange rates in effect at the end of the year, and income and expense items are translated at average exchange rates in effect during the year. The effects of exchange rate fluctuations on the translated amounts of foreign currency assets and liabilities are included as translation adjustments in Accumulated other comprehensive loss within Hubbell shareholders’ equity. Gains and losses from foreign currency transactions are included in results of operations.

Cash and Cash Equivalents

The carrying value of cash equivalents approximates fair value. Cash equivalents consist of highly liquid investments with original maturities to the Company of three months or less.

Investments

Investments in debt and equity securities are classified by individual security as available-for-sale, held-to-maturity or trading securities. Our available-for-sale securities, consisting of municipal bonds and the redeemable preferred stock of a privately held company, are carried on the balance sheet at fair value with current period adjustments to carrying value recorded in Accumulated other comprehensive loss within Hubbell shareholders’ equity, net of tax. Realized gains and losses are recorded in income in the period of sale. The Company’s trading securities are carried on the balance sheet at fair value and consist primarily of debt and equity mutual funds. Gains and losses associated with these trading securities are reflected in the results of operations. The Company did not have any investments classified as held-to-maturity as of December 31, 2017 and 2016.

Accounts Receivable and Allowances

Trade accounts receivable are recorded at the invoiced amount and generally do not bear interest. The allowance for doubtful accounts is based on an estimated amount of probable credit losses in existing accounts receivable. The allowance is calculated based upon a combination of historical write-off experience, fixed percentages applied to aging categories and specific identification based upon a review of past due balances and problem accounts. Account balances are charged off against the allowance when it is determined that internal collection efforts should no longer be pursued. The Company also maintains a reserve for credit memos, cash discounts and product returns which are principally calculated based upon historical experience, specific customer agreements, as well as anticipated future trends.

Inventories

Inventories are stated at the lower of cost or market value. Approximately 71% of total net inventory value is determined utilizing the last-in, first-out (LIFO) method of inventory accounting. The cost of foreign inventories and certain domestic inventories is determined utilizing average cost or first-in, first-out (FIFO) methods of inventory accounting. Reserves for excess and obsolete inventory are provided based on current assessments about future demand compared to on-hand quantities.

Property, Plant, and Equipment

Property, plant, and equipment values are stated at cost less accumulated depreciation. Maintenance and repair expenditures that do not significantly increase the life of an asset are charged to expense when incurred. Property, plant, and equipment placed in service prior to January 1, 1999 are depreciated over their estimated useful lives, principally using accelerated methods. Assets placed in service subsequent to January 1, 1999 are depreciated over their estimated useful lives, using straight-line methods. Leasehold improvements are amortized over the shorter of their economic lives or the lease term. Gains and losses arising on the disposal of property, plant and equipment are included in Operating income in the Consolidated Statement of Income.

Capitalized Computer Software Costs

Capitalized computer software costs, net of amortization, were $15.7 million and $15.6 million at December 31, 2017 and 2016, respectively. This balance is reflected in Other long-term assets in the Consolidated Balance Sheet. Capitalized computer software is for internal use and costs primarily consist of purchased materials and services. Software is amortized on a straight-line basis over appropriate periods, generally five years. The Company recorded amortization expense of $5.6 million in 2017, $5.2 million in 2016 and $4.6 million in 2015 relating to capitalized computer software.

Goodwill and Other Intangible Assets

Goodwill represents purchase price in excess of fair values of the underlying net assets of acquired companies. Indefinite-lived intangible assets and goodwill are subject to annual impairment testing using the specific guidance and criteria described in the accounting guidance. The Company performs its goodwill impairment testing as of April 1st of each year, unless circumstances dictate the need for more frequent assessments. The accounting guidance provides entities an option of performing a qualitative assessment (a "step-zero" test) before performing a quantitative analysis. If the entity determines, on the basis of certain qualitative factors, that it is more-likely-than-not that the goodwill is not impaired, the entity would not need to proceed to the two step goodwill impairment testing process (quantitative analysis) as prescribed in the guidance. The Company applied the "step-zero" test to two of its reporting units. Based on that qualitative assessment, the Company concluded it was more-likely-than-not that the fair value of these reporting units substantially exceeded their carrying value and therefore, further quantitative analysis was not required. For each of the Company's other reporting units the Company has elected to utilize the two step goodwill impairment testing process as permitted in the accounting guidance. Step 1 compares the fair value of the Company’s reporting units to their carrying values. If the fair value of the reporting unit exceeds its carrying value, no further analysis is necessary. If the carrying value of the reporting unit exceeds its fair value, Step 2 must be completed to determine the amount of impairment.

Goodwill impairment testing requires judgment, including the identification of reporting units, assigning assets and liabilities to reporting units and determining the fair value of each reporting unit. Significant judgments required to estimate the fair value of reporting units include estimating future cash flows, determining appropriate discount rates and other assumptions. The Company uses internal discounted cash flow estimates to determine fair value. These cash flow estimates are derived from historical experience and future long-term business plans and the application of an appropriate discount rate. Changes in these estimates and assumptions could materially affect the determination of fair value and/or goodwill impairment for each reporting unit. The Company’s estimated aggregate fair value of its reporting units are reasonable when compared to the Company’s market capitalization on the valuation date.

As of April 1, 2017, our impairment testing resulted in implied fair values for each reporting unit that exceeded the reporting unit’s carrying value, including goodwill. The Company did not have any reporting units at risk of failing Step 1 of the impairment test as the excess of the implied fair value significantly exceeded the carrying value of the reporting units. Additionally, the Company did not have any reporting units with zero or negative carrying amounts. The Company has not recorded any goodwill impairments since the initial adoption of the accounting guidance in 2002.

The Company’s intangible assets consist primarily of customer relationships, tradenames and patents. Intangible assets with definite lives are amortized over periods generally ranging from 5-30 years. The Company amortizes intangible assets with definite lives using either an accelerated method that reflects the pattern in which economic benefits of the intangible assets are consumed and results in higher amortization in the earlier years of the assets useful life, or using a straight line method. Approximately 60% of the gross value of definite-lived intangible assets follow an accelerated amortization method. These definite lived intangibles are tested for impairment whenever events or circumstances indicate that the carrying amount of an asset (asset group) may not be recoverable. An impairment loss is recognized when the carrying amount of an asset exceeds the estimated undiscounted cash flows used in determining the fair value of the asset. The Company did not record any material impairments related to its definite lived intangible assets in 2017, 2016 or 2015. The Company also has some tradenames that are considered to be indefinite-lived intangible assets. These indefinite-lived intangible assets are not amortized and are tested for impairment annually, unless circumstances dictate the need for more frequent assessment.

The accounting guidance related to testing indefinite-lived intangible assets for impairment provides entities an option of performing a qualitative assessment before calculating the fair value of the asset. If the entity determines, on the basis of certain qualitative factors, that it is more-likely-than-not that the asset is not impaired, the entity would not need to calculate the fair value of the asset. The Company performed the qualitative assessment which resulted in no impairment in 2017, 2016 and 2015.

Other Long-Lived Assets

The Company reviews depreciable long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount may not be fully recoverable. If such a change in circumstances occurs, the related estimated future undiscounted cash flows expected to result from the use of the asset group and its eventual disposition is compared to the carrying amount. If the sum of the expected cash flows is less than the carrying amount, an impairment charge is recorded. The impairment charge is measured as the amount by which the carrying amount exceeds the fair value of the asset. The fair value of impaired assets is determined using expected cash flow estimates, quoted market prices when available and appraisals as appropriate. The Company did not record any material impairment charges in 2017, 2016 or 2015.

Accrued Insurance

The Company retains a significant portion of the risks associated with workers’ compensation, medical, automobile and general liability insurance. The Company estimates self-insurance liabilities using a number of factors, including historical claims experience, demographic factors, and other actuarial assumptions. The accrued liabilities associated with these programs are based on the Company’s estimate of the ultimate costs to settle known claims as well as claims incurred but not reported as of the balance sheet date. The Company periodically reviews the assumptions with a third party actuary to determine the adequacy of these self-insurance reserves.

Income Taxes

The Company operates within multiple taxing jurisdictions and is subject to audit in these jurisdictions. The IRS and other tax authorities routinely examine the Company’s tax returns. These audits can involve complex issues which may require an extended period of time to resolve. The Company makes adequate provisions for best estimates of exposures on previously filed tax returns. Deferred income taxes are recognized for the tax consequence of differences between financial statement carrying amounts and the tax basis of assets and liabilities by applying the currently enacted statutory tax rates in accordance with the accounting guidance for income taxes. The effect of a change in statutory tax rates is recognized in the period that includes the enactment date. Additionally, deferred tax assets are required to be reduced by a valuation allowance if it is more-likely-than-not that some portion or all of the deferred tax asset will not be realized. The Company uses factors to assess the likelihood of realization of deferred tax assets such as the forecast of future taxable income and available tax planning strategies that could be implemented to realize the deferred tax assets.

In addition, the accounting guidance prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of the tax position taken or expected to be taken in a tax return. For any amount of benefit to be recognized, it must be determined that it is more-likely-than-not that a tax position will be sustained upon examination by taxing authorities based on the technical merits of the position. The amount of benefit to be recognized is based on the Company’s assertion of the most likely outcome resulting from an examination, including resolution of any related appeals or litigation processes. Companies are required to reflect only those tax positions that are more-likely-than-not to be sustained.

We have accounted for the estimated impact of the TCJA based on the guidance outlined in SAB 118. The accounting for the income tax effects of the TCJA may include provisional amounts during the one-year measurement period from the date of enactment. Accordingly, the Company has included in the current period financial statements a provisional amount with respect to the deemed repatriation provisions of the TCJA, the revaluation of U.S. deferred taxes and the U.S. and foreign tax costs associated with anticipated remittances related to certain of our outside basis differences. We have also included provisional amounts with respect to those states with current conformity to the Internal Revenue Code all of which will be subject to change during the measurement period.

The TCJA also contains a new tax law that may subject the Company to a tax on Global Intangible Low-Taxed Income (GILTI), beginning in 2018. GILTI is a tax on foreign income in excess of a deemed return on tangible assets of foreign corporations. The FASB has provided that Companies subject to GILTI have the option to account for the GILTI tax as a period cost if and when incurred, or to recognize deferred taxes for temporary differences, including outside basis differences, expected to reverse as GILTI. We have elected to account for GILTI as a period cost. See Note 12 — Income Taxes for additional information.

Research and Development

Research and development expenditures represent costs to discover and/or apply new knowledge in developing a new product, process, or in bringing about a significant improvement to an existing product or process. Research and development expenses are recorded as a component of Cost of goods sold. Expenses for research and development were approximately 3% of Cost of goods sold in 2017 and 2% in 2016 and 2015.

Retirement Benefits

The Company maintains various defined benefit pension plans for some of its U.S. and foreign employees. The accounting guidance for retirement benefits requires the Company to recognize the funded status of its defined benefit pension and postretirement plans as an asset or liability in the Consolidated Balance Sheet. Gains or losses, prior service costs or credits, and transition assets or obligations that have not yet been included in net periodic benefit cost as of the end of the year are recognized as components of Accumulated other comprehensive loss, net of tax, within Hubbell shareholders’ equity. The Company’s policy is to fund pension costs within the ranges prescribed by applicable regulations. In addition to providing defined benefit pension benefits, the Company provides health care and life insurance benefits for some of its active and retired employees. The Company’s policy is to fund these benefits through insurance premiums or as actual expenditures are made. See also Note 10 — Retirement Benefits.

Earnings Per Share

Restricted stock granted by the Company is considered a participating security since it contains a non-forfeitable right to dividends. As a result, the earnings per share accounting guidance requires the Company to use the two-class method for calculating earnings per share. The two-class method is an earnings allocation formula that determines earnings per share for common stock and participating securities. Basic earnings per share is calculated as net income available to common shareholders divided by the weighted average number of shares of common stock outstanding. Earnings per diluted share is calculated as net income available to common shareholders divided by the weighted average number of shares outstanding of common stock plus the incremental shares outstanding assuming the exercise of dilutive stock options, stock appreciation rights and performance shares. See also Note 17 — Earnings Per Share.

Stock-Based Compensation

The Company recognizes the grant-date fair value of all stock-based awards on a straight-line basis over their respective requisite service periods (generally equal to an award’s vesting period). A stock-based award is considered vested for expense attribution purposes when the retention of the award is no longer contingent on providing subsequent service. Accordingly, the Company recognizes compensation cost immediately for awards granted to retirement-eligible individuals or over the period from the grant date to the date retirement eligibility is achieved, if less than the stated vesting period. The expense is recorded in Cost of goods sold and S&A expense in the Consolidated Statement of Income based on the recipients’ respective functions within the organization.

The Company records deferred tax assets for awards that will result in deductions on its tax returns, based upon the amount of compensation cost recognized and the statutory tax rate in the jurisdiction in which it will receive a deduction. The Company adopted ASU 2016-09 relating to the accounting for share-based payments on January 1, 2017. The standard requires that differences between the deferred tax assets recognized for financial reporting purposes and the actual tax deduction reported on the Company's tax return be recoded as a component of income tax expense. Prior to the adoption of the standard, differences between the deferred tax assets recognized for financial reporting purposes and the actual tax deduction reported in the Company’s tax return were recognized in Additional paid-in capital to the extent that previously recognized credits to paid-in capital were still available. See also Note 16 — Stock-Based Compensation.

Derivatives

In order to limit financial risk in the management of its assets, liabilities and debt, the Company may use derivative financial instruments such as foreign currency hedges, interest rate hedges and interest rate swaps. All derivative financial instruments are matched with an existing Company asset, liability or proposed transaction. The Company does not speculate or use leverage when trading a derivative product. Market value gains or losses on the derivative financial instrument are recognized in income when the effects of the related price changes of the underlying asset or liability are recognized in income. See Note 13 — Financial Instruments and Fair Value Measurement for more information regarding our derivative instruments.

Recent Accounting Pronouncements

In response to the TCJA, which was signed into law on December 22, 2017, the Securities and Exchange Commission’s Office of the Chief Accountant published SAB 118. SAB 118 addresses the requirements to account for the impact of a change in tax law or tax rates in the period of enactment. Specifically, SAB 118 provides guidance for issuers that are not able to complete the accounting for the income tax effects of the TCJA by the time financial statements are issued for the reporting period that includes the enactment date (“enactment period financials”).

Pursuant to SAB 118, if the accounting for specific income tax effects of the TCJA is incomplete at the time the financial statements are issued, a company should provide a provisional amount for specific income tax effects for which a reasonable estimate can be determined. For any specific income tax effects of the TCJA for which a reasonable estimate cannot be determined because additional information, data, analysis or preparation is required, a company should not report a provisional amount but continue to apply the rules in effect immediately prior to enactment. For income tax effects for which a company was not able to determine a reasonable estimate in the enactment period financials, a provisional amount must be recorded in the first reporting period in which a reasonable estimate can be determined.

Under SAB 118, the measurement period for accounting for the 2017 Act begins in the period of enactment and ends when an entity has obtained, prepared and analyzed the information necessary to complete the accounting requirements under ASC 740 (the “measurement period”), but in no event can the measurement period extend beyond one year from the TCJA’s enactment date. Any provisional amount or adjustment to a provisional amount included in a company’s financial statements during the measurement period should be included in income from continuing operations as an adjustment to tax expense or benefit in the reporting period the amounts are determined.

In March 2017, the Financial Accounting Standards Board ("FASB") issued an Accounting Standards Update (ASU 2017-07) on the presentation of net periodic pension cost and net periodic post-retirement benefit cost. The new guidance requires the service cost component of net periodic pension and post-retirement benefit costs to be reported in the same income statement line item as other employee compensation costs, and the other non-service components to be reported outside of operating income. This new guidance is effective for fiscal years beginning after December 15, 2017 and must be applied on a retrospective basis. Upon adoption, the Company expects 2016 Operating income to increase by $12.0 million and 2017 Operating income to increase by $15.0 million, due to the removal of the non-service components of net periodic pension and post-retirement benefit costs. The Company expects a corresponding increase to Other expense, net, resulting in zero impact to net income in both periods.

In August 2016, the FASB issued an Accounting Standards Update (ASU 2016-15) to provide additional guidance and reduce diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows. The Company adopted the standard during the third quarter of 2017, and the comparable periods within the Consolidated Statements of Cash Flows have been recast to reflect adoption. The adoption did not have a material impact on the Company's financial statements.

In March 2016, the FASB issued an Accounting Standards Update (ASU 2016-09) relating to the accounting for share-based payments. The new guidance requires all income tax effects of share-based awards to be recognized in the income statement when the awards vest or are settled, and allows companies an additional election in the method to estimate forfeitures of share-based payments. The new guidance also requires excess tax benefits to be classified as an operating activity in the statement of cash flows, and cash paid to a tax authority when shares are withheld to satisfy the employer's statutory income tax withholdings be classified as a financing activity. The Company adopted the standard on January 1, 2017. The Company elected to adopt all provisions impacting the Consolidated Statements of Cash Flows retrospectively; as such, the comparable periods within the Consolidated Statements of Cash Flows have been recast to reflect the adoption. The income statement provisions of the new guidance have been adopted prospectively. There is no change to the Company's accounting policy with respect to estimation of forfeitures. The adoption did not have a material impact on the Company's financial statements.

In February 2016, the FASB issued an Accounting Standards Update (ASU 2016-02) related to the accounting and financial statement presentation for leases. This new guidance will require a lessee to recognize a right-to-use asset and a lease liability for both financing and operating leases, with a policy election permitting an exception to this guidance for leases with a term of twelve months or less. For financing leases, the lessee will recognize interest expense and amortization of the right-of-use asset, and for operating leases, the lessee will recognize a straight-line lease expense. This guidance is effective for fiscal years beginning after December 15, 2018, with early adoption permitted. The new standard must be adopted using a modified retrospective transition at the beginning of the earliest comparative period presented. The Company expects to recognize approximately $100 million of right-of-use assets and corresponding lease liabilities on the balance sheet upon adoption. The Company does not expect the adoption will have a material impact on results of operations.

In May 2014, the FASB issued an Accounting Standards Update (ASU 2014-09) related to new revenue recognition guidance that supersedes the existing revenue recognition guidance and most industry-specific guidance applicable to revenue recognition. According to the new guidance, an entity will apply a principles-based five step model to recognize revenue upon the transfer of promised goods or services to customers and in an amount that reflects the consideration for which the entity expects to be entitled in exchange for those goods or services. Subsequently, the FASB has issued amendments to certain aspects of the guidance including the effective date. The Company will adopt the guidance in the first quarter of 2018 using the modified-retrospective method.

Based on the reviews and assessments performed to date, the Company expects the pattern of revenue recognition for substantially all of its businesses to be unchanged, and that upon adoption revenue will generally continue to be recognized at a single point in time when control is transferred to the customer. The Company anticipates an immaterial impact to retained earnings upon adoption, as well as an immaterial balance sheet impact related to the classification of amounts associated with sales returns reserves.

Business Acquisitions

12 Months Ended

Dec. 31, 2017

Business Combinations [Abstract]

Business Acquisitions

In the first quarter of 2017, the Company completed two acquisitions for $10.1 million, net of cash received, resulting in the recognition of intangible assets of $3.4 million and goodwill of $5.0 million. The $3.4 million of intangible assets consists primarily of customer relationships and trade names that will be amortized over a weighted average period of approximately 13 years. These acquisitions have been added to the Power segment and $2.7 million of the goodwill related to one of the acquisitions is currently expected to be deductible for tax purposes.

In the second quarter of 2017, the Company acquired all of the issued and outstanding limited liability company interests in iDevices, LLC ("iDevices") for $59.2 million. iDevices is a developer with embedded firmware and application development expertise with custom-built Internet of Things ("IoT") Cloud infrastructure. The iDevices acquisition adds capabilities and expertise in IoT technology that is required to provide Tier 3 energy management solutions via connected hardware with a software front-end. iDevices is reported in the Electrical segment. We have recognized intangible assets of $9.6 million and goodwill of $45.9 million as a result of this acquisition. The $9.6 million of intangible assets consists primarily of developed technology, customer relationships and trade names and will be amortized over a weighted average period of approximately 12 years. All of the goodwill is expected to be deductible for tax purposes.

In the second quarter of 2017, the Company also acquired substantially all of the assets of Advance Engineering Corporation and related companies (collectively "AEC") for $32.5 million. AEC is a gas components manufacturer that complements the Company's existing business in the natural gas distribution vertical. AEC joins the Company's recent acquisitions of GasBreaker and Lyall to bolster its main-to-meter mechanical solutions in this area, and along with Continental Industries, makes up our offering in the gas vertical. AEC is reported in the Electrical segment. We have recognized intangible assets of $16.8 million and goodwill of $12.8 million as a result of this acquisition. The $16.8 million of intangible assets consists primarily of customer relationships and trade names and will be amortized over a weighted average period of approximately 18 years. All of the goodwill is expected to be deductible for tax purposes.

In the fourth quarter of 2017, the Company acquired all of the issued and outstanding shares of Meramec Instrument Transformer Company ("Meramec") for $69.7 million. Meramec produces instrument current transformers for the power generator, power transformer, and the high and medium-voltage circuit breaker markets. Meramec is reported within the Power segment. We have recognized intangible assets of $33.8 million and goodwill of $24.8 million as a result of this acquisition. The $33.8 million of intangible assets consists primarily of customer relationships, trade names, and developed software and will be amortized over a weighted average period of approximately 21 years. All of the goodwill is expected to be deductible for tax purposes.

These business acquisitions have been accounted for as business combinations and have resulted in the recognition of goodwill. The goodwill relates to a number of factors built into the purchase price, including the future earnings and cash flow potential of the businesses as well as the complementary strategic fit and resulting synergies they bring to the Company’s existing operations.

The following table summarizes the preliminary fair values of the assets acquired and liabilities assumed at the date of acquisition related to all transactions (in millions):



Tangible assets acquired	$	34.4
Intangible assets	63.6
Goodwill	88.5
Net deferred taxes	(0.2		)
Other liabilities assumed	(14.8		)
TOTAL CONSIDERATION, NET OF CASH RECEIVED	$	171.5

The Consolidated Financial Statements include the results of operations of the acquired businesses from their respective dates of acquisition. Net sales and earnings related to these acquisitions for the year ended December 31, 2017 were not significant to the consolidated results. Pro forma information related to these acquisitions has not been included because the impact to the Company’s consolidated results of operations was not material.

Cash used for the acquisition of businesses, net of cash acquired as reported in the Consolidated Statement of Cash Flows for the twelve months ended December 31, 2017 is $184.1 million and includes payments associated with a 2016 acquisition for which the purchase price is due to be settled in installments through 2019.

Subsequent Event - Acquisition of Aclara

In February 2018, the Company completed the acquisition of Aclara for $1.1 billion in an all-cash transaction. Aclara will be added to the Power segment. To fund the Aclara acquisition, on February 2, 2018 the Company borrowed $500 million under a Term Loan Agreement with a syndicate of lenders, issued $450 million of long-term, unsecured, unsubordinated notes maturing in 2028, and the remaining purchase price and transaction expenses were funded with commercial paper. Refer to Note 11 — Debt and Note 23 — Subsequent Events in the Notes to Consolidated Financial Statements for additional information.

Receivables and Allowances

12 Months Ended

Dec. 31, 2017

Accounts, Notes, Loans and Financing Receivable, Net, Current [Abstract]

Receivables and Allowances

Receivables consist of the following components at December 31, (in millions):



	2017			2016
Trade accounts receivable	$	576.3		$	565.5
Non-trade receivables	19.1			15.1
Accounts receivable, gross	595.4			580.6
Allowance for credit memos, returns and cash discounts	(50.5		)	(45.9		)
Allowance for doubtful accounts	(4.6		)	(4.7		)
Total allowances	(55.1		)	(50.6		)
ACCOUNTS RECEIVABLE, NET	$	540.3		$	530.0

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References + Details

Goodwill and Other Intangible Assets

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill And Other Intangible Assets

Goodwill and Other Intangible Assets

Changes in the carrying amounts of goodwill for the years ended December 31, 2017 and 2016, by segment, were as follows (in millions):



	Segment
	Electrical			Power		Total
BALANCE AT DECEMBER 31, 2015	$	611.2		$	317.3	$	928.5
Current year acquisitions	49.4			20.6		70.0
Foreign currency translation and prior year acquisitions	(8.6		)	1.1		(7.5		)
BALANCE AT DECEMBER 31, 2016	$	652.0		$	339.0	$	991.0
Current year acquisitions	58.7			29.8		88.5
Foreign currency translation and prior year acquisitions	6.9			2.6		9.5
BALANCE AT DECEMBER 31, 2017	$	717.6		$	371.4	$	1,089.0

In 2017, the Company completed multiple acquisitions. These acquisitions have been accounted for as business combinations and have resulted in the recognition of $88.5 million of goodwill. See also Note 2 — Business Acquisitions.

The Company has not recorded any material goodwill impairments since the initial adoption of the accounting guidance in 2002.

Identifiable intangible assets are recorded in Intangible assets, net in the Consolidated Balance Sheet. Identifiable intangible assets are comprised of the following (in millions):



	December 31, 2017					December 31, 2016
	Gross Amount		Accumulated Amortization			Gross Amount		Accumulated Amortization
Definite-lived:
Patents, tradenames and trademarks	$	151.4	$	(50.1	)	$	143.7	$	(43.4	)
Customer/agent relationships and other	462.0		(156.7		)	405.9		(128.0		)
TOTAL DEFINITE-LIVED INTANGIBLES	613.4		(206.8		)	549.6		(171.4		)
Indefinite-lived:
Tradenames and other	53.8		—			53.3		—
TOTAL INTANGIBLE ASSETS	$	667.2	$	(206.8	)	$	602.9	$	(171.4	)

Amortization expense associated with these definite-lived intangible assets was $34.9 million, $32.3 million and $28.2 million in 2017, 2016 and 2015, respectively. Amortization expense associated with these intangible assets is expected to be $35.7 million in 2018, $33.2 million in 2019, $33.8 million in 2020, $33.2 million in 2021 and $31.7 million in 2022.

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Investments

12 Months Ended

Dec. 31, 2017

Investments [Abstract]

Investments

At December 31, 2017 and December 31, 2016, the Company held investments classified as available-for-sale and investments classified as trading securities. Investments classified as available-for-sale consisted of municipal bonds with an amortized cost basis of $54.3 million and an investment in the redeemable preferred stock of a privately-held electrical utility substation security provider with an amortized cost basis of $5.0 million. The investment in redeemable preferred stock was classified in Level 3 of the fair value hierarchy and had a fair value of $4.1 million and $3.8 million at December 31, 2017 and 2016, respectively. Investments classified as trading securities were comprised primarily of debt and equity mutual funds and are stated at fair market value based on current quotes.

The following table sets forth selected data with respect to the Company’s investments at December 31, (in millions):



	2017											2016
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Carrying Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Carrying Value
Available-for-sale securities	$	59.3	$	0.1	$	(1.0	)	$	58.4	$	58.4	$	58.6	$	0.3	$	(1.5	)	$	57.4	$	57.4
Trading securities	8.9		4.9		—			13.8		13.8		7.1		3.1		—			10.2		10.2
TOTAL INVESTMENTS	$	68.2	$	5.0	$	(1.0	)	$	72.2	$	72.2	$	65.7	$	3.4	$	(1.5	)	$	67.6	$	67.6

Contractual maturities of our investments in available-for-sale securities at December 31, 2017 were as follows (in millions):



	Amortized Cost		Fair Value
Available-for-sale securities
Due within 1 year	$	14.5	$	14.5
After 1 year but within 5 years	31.5		30.7
After 5 years but within 10 years	10.9		10.8
Due after 10 years	2.4		2.4
TOTAL	$	59.3	$	58.4

The total unrealized gain/(loss) recognized in the year relating to available-for-sale securities, net of tax, was $0.6 million and $(0.9) million at December 31, 2017 and 2016, respectively. These net unrealized gains/(losses) are included in Accumulated other comprehensive loss, net of tax. Net unrealized gains relating to trading securities have been reflected in the results of operations. The Company uses the specific identification method when identifying the cost basis used to calculate the gain or loss on these securities. Gains and losses for both available-for-sale and trading securities were not material in 2017, 2016 and 2015.

Property, Plant and Equipment

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Property, Plant, and Equipment

Property, plant, and equipment, carried at cost, is summarized as follows at December 31, (in millions):



	2017			2016
Land	$	40.0		$	43.1
Buildings and improvements	272.2			268.7
Machinery, tools, and equipment	806.2			784.7
Construction-in-progress	43.4			36.9
Gross property, plant, and equipment	1,161.8			1,133.4
Less accumulated depreciation	(703.5		)	(693.6		)
NET PROPERTY, PLANT, AND EQUIPMENT	$	458.3		$	439.8

Depreciable lives on buildings range between 20-45 years. Depreciable lives on machinery, tools, and equipment range between 3-15 years. The Company recorded depreciation expense of $57.5 million, $53.4 million and $51.2 million for 2017, 2016 and 2015, respectively.

Retirement Benefits

12 Months Ended

Dec. 31, 2017

Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]

Retirement Benefits

The Company has funded and unfunded non-contributory U.S. and foreign defined benefit pension plans. Benefits under these plans are generally provided based on either years of service and final average pay or a specified dollar amount per year of service. The U.S. defined benefit pension plan has been closed to new participants since 2004, while the Canadian and UK defined benefit pension plans have been closed to new entrants since 2006 and 2007, respectively. These U.S., Canadian and UK employees are eligible instead for defined contribution plans.

The Company also has a number of health care and life insurance benefit plans covering eligible employees who reached retirement age while working for the Company. These benefits have been discontinued for substantially all future retirees. The Company anticipates future cost-sharing charges for its discontinued plans that are consistent with past practices.The Company uses a December 31 measurement date for all of its plans.

In December 2016, the Company approved amendments to the domestic qualified defined benefit pension plan and non-qualified defined benefit plan, which froze service accruals for active participants effective February 28, 2017 and further will freeze compensation accruals effective December 31, 2020. The Company also froze all accruals in a second non-qualified defined benefit plan effective December 31, 2016.

As a result of these amendments, the Company recognized a $34.1 million curtailment gain in Accumulated other comprehensive income as of December 31, 2016 and also recognized $0.2 million of pension expense in 2016 associated with previously unrecognized prior service costs. In addition, effective January 1, 2017, the amortization of actuarial gains and losses of these plans is being recognized over the remaining life expectancy of participants, as all participants are considered inactive as a result of the amendment.

In 2016, we also completed a transaction with a third-party insurer to settle approximately $40 million of projected benefit obligation of our domestic qualified defined benefit pension plans.

In 2015, we amended our domestic qualified defined benefit pension plans to offer a voluntary lump sum pension payout program to certain eligible terminated vested participants that would settle our obligation to those participants accepting the offer. As part of this voluntary lump sum program, in 2015 the Company made approximately $27.7 million of payments to participants, settling its pension obligation by approximately the same amount. There were no other amendments made in 2017 or 2016 to the defined benefit pension plans which had a significant impact on the total pension benefit obligation.

The Company's U.S. defined benefit pension plans were approximately 88% of the $956.1 million total pension benefit obligations at December 31, 2017.

The following table sets forth the reconciliation of beginning and ending balances of the benefit obligations and the plan assets for the Company’s defined benefit pension and other benefit plans at December 31, (in millions):



	Pension Benefits						Other Benefits
	2017			2016			2017			2016
Change in benefit obligation
Benefit obligation at beginning of year	$	917.4		$	912.3		$	26.2		$	26.6
Service cost	5.9			12.9			0.1			—
Interest cost	37.2			41.9			1.0			1.2
Plan participants’ contributions	0.6			0.5			—			—
Amendments	0.3			(34.1		)	—			—
Actuarial loss	29.7			88.0			1.4			0.2
Currency impact	9.7			(18.5		)	—			—
Other	(0.4		)	(0.5		)	—			—
Benefits paid	(44.3		)	(85.1		)	(1.7		)	(1.8		)
Benefit obligation at end of year	$	956.1		$	917.4		$	27.0		$	26.2
Change in plan assets
Fair value of plan assets at beginning of year	$	705.1		$	757.6		$	—		$	—
Actual return on plan assets	58.6			23.6			—			—
Employer contributions	9.8			24.3			1.7			1.8
Plan participants’ contributions	0.6			0.5			—			—
Currency impact	9.0			(15.8		)	—			—
Benefits paid	(44.3		)	(85.1		)	(1.7		)	(1.8		)
Fair value of plan assets at end of year	$	738.8		$	705.1		$	—		$	—
FUNDED STATUS	$	(217.3	)	$	(212.3	)	$	(27.0	)	$	(26.2	)
Amounts recognized in the consolidated balance sheet consist of:
Prepaid pensions (included in Other long-term assets)	$	1.5		$	1.7		$	—		$	—
Accrued benefit liability (short-term and long-term)	(218.8		)	(214.0		)	(27.0		)	(26.2		)
NET AMOUNT RECOGNIZED IN THE CONSOLIDATED BALANCE SHEET	$	(217.3	)	$	(212.3	)	$	(27.0	)	$	(26.2	)
Amounts recognized in Accumulated other comprehensive loss (income) consist of:
Net actuarial loss	$	270.1		$	274.2		$	3.0		$	1.7
Prior service cost (credit)	0.6			0.4			(2.3		)	(3.3		)
NET AMOUNT RECOGNIZED IN ACCUMULATED OTHER COMPREHENSIVE LOSS	$	270.7		$	274.6		$	0.7		$	(1.6	)

The accumulated benefit obligation for all defined benefit pension plans was $924.6 million and $876.2 million at December 31, 2017 and 2016, respectively. Information with respect to plans with accumulated benefit obligations in excess of plan assets is as follows, (in millions):



	2017		2016
Projected benefit obligation	$	842.7	$	801.1
Accumulated benefit obligation	$	826.5	$	781.4
Fair value of plan assets	$	626.3	$	603.1

The following table sets forth the components of pension and other benefit costs for the years ended December 31, (in millions):



	Pension Benefits									Other Benefits
	2017			2016			2015			2017			2016			2015
Components of net periodic benefit cost:
Service cost	$	5.9		$	12.9		$	17.7		$	0.1		$	—		$	0.1
Interest cost	37.2			41.9			40.5			1.0			1.2			1.0
Expected return on plan assets	(34.1		)	(44.3		)	(53.2		)	—			—			—
Amortization of prior service cost (credit)	0.1			0.1			0.2			(1.0		)	(1.0		)	(1.0		)
Amortization of actuarial losses (gains)	11.4			13.9			12.1			—			—			(0.1		)
Curtailment and settlement losses	0.4			0.2			—			—			—			—
Net periodic benefit cost	$	20.9		$	24.7		$	17.3		$	0.1		$	0.2		$	—
Changes recognized in other comprehensive loss (income), before tax:
Current year net actuarial loss	$	4.2		$	72.0		$	37.0		$	1.4		$	0.2		$	0.5
Current year prior service credit	0.3			—			—			—			—			—
Amortization of prior service (cost) credit	(0.1		)	(0.1		)	(0.2		)	1.0			1.0			1.0
Amortization of net actuarial (losses) gains	(11.4		)	(13.9		)	(12.1		)	—			—			0.1
Currency impact	3.5			(4.0		)	(0.1		)	—			—			—
Other adjustments	(0.4		)	(0.2		)	—			—			—			—
Total recognized in other comprehensive loss	(3.9		)	53.8			24.6			2.4			1.2			1.6
TOTAL RECOGNIZED IN NET PERIODIC PENSION COST AND OTHER COMPREHENSIVE LOSS	$	17.0		$	78.5		$	41.9		$	2.5		$	1.4		$	1.6
Amortization expected to be recognized through income during 2018
Amortization of prior service cost (credit)	$	0.1								$	(1.0	)
Amortization of net loss	10.9									0.2
TOTAL EXPECTED TO BE RECOGNIZED THROUGH INCOME DURING NEXT FISCAL YEAR	$	11.0								$	(0.8	)

The Company also maintains six defined contribution pension plans. The total cost of these plans was $19.8 million in 2017, $15.6 million in 2016 and $13.3 million in 2015, excluding the employer match for the 401(k) plan. This cost is not included in the above net periodic benefit cost for the defined benefit pension plans.

The Company participated in two multi-employer defined benefit pension plans under the terms of collective-bargaining agreements that cover its union represented employees at December 31, 2016. In 2017, the Company withdrew from one of these plans. The Company’s total contributions to these plans were $0.4 million in 2017, $0.5 million in 2016, and $0.8 million in 2015. These contributions represent more than five percent of the total contributions made to one of these plans in 2017, 2016 and 2015.

The risks of participating in multi-employer plans are different from single-employer plans in that assets contributed are pooled and may be used to provide benefits to employees of other participating employers. If a participating employer stops contributing to the plan, the unfunded obligations of the plan may have to be assumed by the remaining participant employers. If we choose to stop participating in a multi-employer plan we may be required to pay those plans a withdrawal liability based on the unfunded status of the plan.

In the fourth quarter of 2016, the Company recorded a charge of $12.5 million in Cost of goods sold representing the estimated withdrawal liability from one of the multi-employer plans. Depending on actions of third parties, including bankruptcy or withdrawals from the multi-employer plan, under terms customary to multi-employer plans, it is possible that the Company could in the future be subject to certain additional liabilities associated with its participation and withdraw from the multi-employer pension plan, which the Company estimates could be up to an additional $23 million as of December 31, 2017.

Assumptions

The following assumptions were used to determine the projected benefit obligations at the measurement date and the net periodic benefit cost for the year:



	Pension Benefits						Other Benefits
	2017		2016		2015		2017		2016		2015
Weighted-average assumptions used to determine benefit obligations at December 31,
Discount rate	3.67	%	4.12	%	4.71	%	3.70	%	4.10	%	4.60	%
Rate of compensation increase	3.24	%	3.55	%	3.59	%	4.00	%	3.93	%	3.92	%
Weighted-average assumptions used to determine net periodic benefit cost for years ended December 31,
Discount rate	4.12	%	4.71	%	4.23	%	4.10	%	4.60	%	4.10	%
Expected return on plan assets	4.94	%	6.04	%	6.36	%	N/A		N/A		N/A
Rate of compensation increase	3.55	%	3.59	%	3.15	%	3.93	%	3.92	%	3.60	%

At the end of each year, the Company determines the appropriate expected return on assets for each plan based upon its strategic asset allocation (see discussion below). In making this determination, the Company utilizes expected returns for each asset class based upon current market conditions and expected risk premiums for each asset class.

The Company also determines the discount rate to be used to calculate the present value of pension plan liabilities at the end of each year. The discount rate for the Company’s U.S. and Canadian pension plans is determined by matching the expected cash flows associated with its benefit obligations to the expected cash flows of a hypothetical portfolio of high quality, fixed income debt instruments with maturities that closely match the expected funding period of its pension liabilities. As of December 31, 2017, the Company used a discount rate of 3.80% for its U.S. pension plans compared to a discount rate of 4.30% used in 2016. For its Canadian pension plan, the Company used a discount rate of 3.50% as of December 31, 2017 compared to the 3.85% discount rate used in 2016.

For its UK pension plan the discount rate was derived using a yield curve fitted to the yields on AA bonds in the Barclays Capital Sterling Aggregate Corporate Index and uses sample plan cash flow data as a proxy to plan specific liability cash flows. The derived discount rate is the single discount rate equivalent to discounting these liability cash flows at the term-dependent spot rate of AA corporate bonds. This methodology resulted in a December 31, 2017 discount rate for the UK pension plan of 2.60% as compared to a discount rate of 2.70% used in 2016.

In 2017 we changed the mortality table used to calculate the present value of U.S. benefit obligations from the RP-2000 mortality table with generational projection using Scale BB-2D to the RP-2014 mortality table, with generational projection from 2006 using Scale MP-2017. That change resulted in an approximately $15 million decrease in the projected benefit obligation of our U.S. plans upon remeasurement at December 31, 2017. The RP-2014 mortality table with generational projection from 2006 using Scale MP-2017 was chosen as the best estimate based on the observed and anticipated experience of the plans after considering alternative tables.

The rate of compensation increase assumption reflects the Company’s actual experience and best estimate of future increases.

The assumed health care cost trend rates used to determine the projected postretirement benefit obligation are as follows:



	Other Benefits
	2017		2016		2015
Assumed health care cost trend rates at December 31,
Health care cost trend assumed for next year	7.0	%	7.2	%	7.4	%
Rate to which the cost trend is assumed to decline	5.0	%	5.0	%	5.0	%
Year that the rate reaches the ultimate trend rate	2028		2028		2028

Assumed health care cost trend rates have an effect on the amounts reported for the postretirement benefit plans. A one-percentage-point change in assumed health care cost trend rates would have the following effects (in millions):



	One Percentage Point Increase		One Percentage Point Decrease
Effect on total of service and interest cost	$	0.1	$	(0.1	)
Effect on postretirement benefit obligation	$	1.8	$	(1.5	)

Plan Assets

The Company’s combined targeted 2018 weighted average asset allocation for domestic and foreign pension plans and the actual weighted average asset allocation for domestic and foreign pension plans at December 31, 2017 and 2016 by asset category are as follows:



	Percentage of Plan Assets
	Target		Actual
Asset Category	2018		2017		2016
Equity securities	19	%	18	%	16	%
Debt securities & Cash	64	%	65	%	65	%
Alternative Investments	17	%	17	%	19	%
TOTAL	100	%	100	%	100	%

At the end of each year, the Company estimates the expected long-term rate of return on pension plan assets based on the strategic asset allocation for its plans. In making this determination, the Company utilizes expected rates of return for each asset class based upon current market conditions and expected risk premiums for each asset class. The Company has written investment policies and asset allocation guidelines for its domestic and foreign pension plans. In establishing these policies, the Company has considered that its various pension plans are a major retirement vehicle for most plan participants and has acted to discharge its fiduciary responsibilities with regard to the plans solely in the interest of such participants and their beneficiaries. The goal underlying the establishment of the investment policies is to provide that pension assets shall be invested in a prudent manner and so that, together with the expected contributions to the plans, the funds will be sufficient to meet the obligations of the plans as they become due. To achieve this result, the Company conducts a periodic strategic asset allocation study to form a basis for the allocation of pension assets between various asset categories. Specific policy benchmark percentages are assigned to each asset category with minimum and maximum ranges established for each. The assets are then tactically managed within these ranges. Equity securities include investments in large-cap, mid-cap and small-cap companies located inside and outside the United States. Fixed income securities include corporate bonds of companies from diversified industries, mortgage-backed securities and US Treasuries. Derivative investments include futures contracts used by the plan to adjust the level of its investments within an asset allocation category. The actual and target percentages reported in the preceding table reflect the economic exposure to each asset category, including the impact of derivative positions. All futures contracts are 100% supported by cash or cash equivalent investments. At no time may derivatives be utilized to leverage the asset portfolio. Equity securities include $40.0 million of Company common stock (6.6% of total domestic plan assets) at December 31, 2016. At December 31, 2017, there were no holdings of Company stock in pension plan assets.

The Company’s other post-employment benefits are unfunded; therefore, no asset information is reported.

The fair value of the Company’s pension plan assets at December 31, 2017 and 2016, by asset category are as follows (in millions):



				Quoted Prices in Active Markets for Identical Assets		Quoted Prices in Active Market for Similar Asset			Significant Unobservable Inputs		Investments Priced Using Net Asset Value
Asset Category	Total			(Level 1)		(Level 2)			(Level 3)
Cash and cash equivalents	$	47.9		$	47.9	$	—		$	—	$	—
Equity securities:
US Large-cap ^(a)	15.6			15.6		—			—		—
US Mid-cap and Small-cap Growth ^(b)	3.1			3.1		—			—		—
International Large-cap	30.9			30.9		—			—		—
Emerging Markets ^(c)	8.6			8.6		—			—		—
Fixed Income Securities:
US Treasuries	402.2			—		402.2			—		—
Corporate Bonds^(d)	10.6			0.3		10.3			—		—
Asset Backed Securities and Other	75.6			—		75.6			—		—
Derivatives:
Assets ^(e)	4.6			1.5		3.1			—		—
(Liabilities) ^(e)	(1.3		)	0.1		(1.4		)	—		—
Alternative Investment Funds ^(f)	123.0			50.6		—			—		72.4
Common Pooled Fund ^(g)	18.0			0.8		17.2			—		—
BALANCE AT DECEMBER 31, 2017	$	738.8		$	159.4	$	507.0		$	—	$	72.4



				Quoted Prices in Active Markets for Identical Assets			Quoted Prices in Active Market for Similar Asset			Significant Unobservable Inputs		Investments Priced Using Net Asset Value
Asset Category	Total			(Level 1)			(Level 2)			(Level 3)
Cash and cash equivalents	$	48.3		$	48.3		$	—		$	—	$	—
Equity securities:
US Large-cap ^(a)	29.5			29.5			—			—		—
US Mid-cap and Small-cap Growth^(b)	42.6			42.6			—			—		—
International Large-cap	27.6			27.6			—			—		—
Emerging Markets ^(c)	5.9			5.9			—			—		—
Fixed Income Securities:
US Treasuries	334.5			—			334.5			—		—
Corporate Bonds ^(d)	21.0			0.3			20.6			0.1		—
Asset Backed Securities and Other	45.0			—			45.0			—		—
Derivatives:
Assets ^(e)	2.1			0.5			1.6			—		—
(Liabilities) ^(e)	(1.1		)	(0.5		)	(0.6		)	—		—
Alternative Investment Funds ^(f)	133.5			47.0			—			—		86.5
Common Pooled Funds ^(g)	16.2			0.8			15.4			—		—
BALANCE AT DECEMBER 31, 2016	$	705.1		$	202.0		$	416.5		$	0.1	$	86.5


(a)	Includes an actively managed portfolio of large-cap US stocks.


(b)	Includes $40.0 million of the Company’s common stock at December 31, 2016, and an investment in a small cap open ended mutual fund.


(c)	Includes open ended emerging markets mutual funds.


(d)	Includes primarily investment grade bonds from diverse industries.


(e)	Includes primarily U.S. and foreign equity futures as well as foreign fixed income futures and positions in U.S. Treasury futures to adjust the duration of the portfolio.


(f)	Includes investments in hedge funds, including fund of funds products and open end mutual funds.


(g)	Investments in Common Pooled Funds, consisting of equities and fixed income securities.

Investments Priced Using Net Asset Value ("NAV") within Alternative Investment Funds in the preceding tables consist of fund of fund products. These products invest in a number of investment funds managed by a diversified group of third-party investment managers who employ a variety of alternative investment strategies, including relative value, security selection, distressed value, global macro, specialized credit and directional strategies. The objective of these funds is to achieve the desired capital appreciation with lower volatility than either traditional equity or fixed income securities.

Contributions

Although not required under the Pension Protection Act of 2006, the Company may make voluntary contributions to its qualified defined benefit pension plans in 2018. The Company expects to contribute approximately $1.9 million to its foreign plans in 2018.

Estimated Future Benefit Payments

The following domestic and foreign benefit payments, which reflect future service, as appropriate, are expected to be paid as follows, (in millions):



	Pension Benefits		Other Benefits
2018	$	42.9	$	2.4
2019	$	44.4	$	2.3
2020	$	46.1	$	2.2
2021	$	47.6	$	2.2
2022	$	49.8	$	2.0
2023-2027	$	267.2	$	8.8

Debt

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Debt

The following table sets forth the Company’s long-term debt at December 31, (in millions):



	Maturity	2017		2016
Senior notes at 5.95%, net of unamortized discount and unamortized debt issuance costs	2018	$	—	$	299.3
Senior notes at 3.625%, net of unamortized discount and unamortized debt issuance costs	2022	297.9		297.5
Senior notes at 3.35%, net of unamortized discount and unamortized debt issuance costs	2026	394.4		393.7
Senior notes at 3.15%, net of unamortized discount and unamortized debt issuance costs	2027	294.8		—
TOTAL LONG-TERM DEBT		$	987.1	$	990.5

In August 2017, the Company completed a public debt offering of $300 million of long-term unsecured, unsubordinated notes maturing in August 2027 and bearing interest at a fixed rate of 3.15% (the "2027 Notes"). Net proceeds from the issuance were $294.6 million after deducting the discount on the notes and offering expenses paid by the Company.

In September 2017, the Company applied the net proceeds from the 2027 Notes to redeem all of its $300 million outstanding long-term, unsecured, unsubordinated notes maturing in 2018 and bearing interest at a fixed rate of 5.95% (the "2018 Notes"). In connection with this redemption, the Company recognized a loss on the early extinguishment of the 2018 Notes of $10.1 million on a before-tax basis.

In March 2016, the Company completed a public debt offering of $400 million of long-term unsecured, unsubordinated notes maturing in March 2026 and bearing interest at a fixed rate of 3.35% (the "2026 Notes"). Net proceeds from the issuance were $393.4 million after deducting the discount on the notes and offering expenses paid by the Company.

In November 2010, the Company completed a public debt offering for $300 million of long-term unsecured, unsubordinated notes maturing in November 2022 (“2022 Notes”) and bearing interest at a fixed rate of 3.625%. Prior to the issuance of the 2022 Notes, the Company entered into a forward interest rate lock which resulted in a $1.6 million loss. This amount was recorded in Accumulated other comprehensive loss, net of tax, and is being amortized over the life of the 2022 Notes.

The 2022 Notes, 2026 Notes and 2027 Notes are all fixed rate indebtedness, are callable at any time with a make whole premium and are only subject to accelerated payment prior to maturity in the event of a default (including as a result of the Company's failure to meet certain non-financial covenants) under the indenture governing the notes, as modified by the supplemental indentures creating such notes, or upon a change in control triggering event as defined in such indenture. The Company was in compliance with all non-financial covenants as of December 31, 2017.

At December 31, 2017 and 2016, the Company had $68.1 million and $3.2 million, respectively, of short-term debt outstanding.

Short-term debt at December 31, 2017 includes $63.0 million of commercial paper borrowing, which was used to fund the purchase of Meramec. There were no commercial paper borrowings outstanding at December 31, 2016.

Short-term debt at December 31, 2017 and 2016 also includes $5.1 million and $3.2 million, respectively of other borrowings to support our international operations in China and Brazil.

Other information related to short-term debt at December 31, is summarized below:



	2017		2016
Interest rate on short-term debt:
At year end^(a)	1.95	%	6.89	%
Paid during the year (weighted average)	2.24	%	0.72	%


(a)	The interest rate at December 31, 2016 reflects short term borrowings which are predominately related to our operations in China and Brazil and reflect market interest rates in those regions.

On December 16, 2015, the Company entered into a five-year revolving credit agreement (the "2015 Credit Facility') with a syndicate of lenders that provides a $750 million committed revolving credit facility. The revolving 2015 Credit Facility serves as a backup to the Company's commercial paper program. Commitments under the 2015 Credit Facility may be increased to an aggregate amount not the exceed $1.250 billion. The interest rate applicable to borrowings under the 2015 Credit Facility is generally either the adjusted LIBOR plus an applicable margin (determined by reference to a ratings based grid) or the alternative base rate.

The single financial covenant in the 2015 Credit Facility, which the Company is in compliance with as of December 31, 2017, requires that total debt not exceed 55% of total capitalization as of the last day of each fiscal quarter of the Company.

Annual commitment fees to support availability under the 2015 Credit Facility are not material. As of December 31, 2017 the 2015 Credit Facility has not been drawn against.

The Company also maintains other lines of credit that are primarily used to support the issuance of letters of credit. Interest rates and other terms of borrowing under these lines of credit vary from country to country, depending on local market conditions. At December 31, 2017 and 2016 these lines totaled $53.9 million and $51.4 million, respectively, of which $21.5 million and $21.0 million was utilized to support letters of credit and the remaining amount was unused. The annual commitment fees associated with these lines of credit are not material.

Interest and fees paid related to total indebtedness was $47.9 million, $37.1 million and $29.5 million in 2017, 2016 and 2015, respectively. The $47.9 million paid in 2017 includes $9.9 million related to the make whole payment for the extinguishment of the 2018 Notes.

Subsequent Event - Funding for the Aclara acquisition and new five-year credit facility

On February 2, 2018, the Company completed a public offering of $450 million of long-term unsecured, unsubordinated notes maturing in February 2028 and bearing interest at a fixed rate of 3.5% (the "2028 Notes"). Net proceeds from the issuance were $442.6 million after deducting the discount on the notes and offering expenses paid by the Company. The 2028 Notes are fixed rate indebtedness, are callable at any time with a make whole premium and are only subject to accelerated payment prior to maturity in the event of a default (including as a result of the Company's failure to meet certain non-financial covenants) under the indenture governing the 2028 Notes, as modified by the supplemental indenture creating such notes, or upon a change in control triggering event as defined in such indenture.

On January 31, 2018, the Company entered into a Term Loan Agreement (the "Term Loan Agreement") with a syndicate of lenders. The Term Loan Agreement provided the Company, with the ability to borrow, in a single borrowing on the Aclara acquisition date, up to $500 million on an unsecured basis to partially finance the Aclara acquisition (the "Term Loan"). On February 2, 2018, the Company borrowed $500 million under the Term Loan Agreement to fund the Aclara acquisition. The interest rate applicable to borrowings under the Term Loan Agreement is generally either the adjusted LIBOR plus an applicable margin (determined by reference to a ratings based grid) or the alternate base rate. Borrowings under the Term Loan Agreement will amortize in equal quarterly installments of 5% per year in year one, 5% per year in year two, 7.5% per year in year three, 10% per year in year four, 10% per year in year five, and any remaining borrowings under the Term Loan Agreement are due and payable in full in February 2023. The single financial covenant in the Term Loan Agreement requires that total debt not exceed 65% of total capitalization as of the last day of each fiscal quarter of the Company.

On January 31, 2018 the Company entered into a new five-year revolving credit agreement (the "2018 Credit Facility") with a syndicate of lenders that provides a $750 million committed revolving credit facility. In connection with the acquisition, the Company terminated all commitments under the 2015 Credit Facility. Commitments under the 2018 Credit Facility may be increased to an aggregate amount not to exceed $1.250 billion. The interest rate applicable to borrowings under the 2018 Credit Facility is generally either the adjusted LIBOR plus an applicable margin (determined by reference to a ratings based grid) or the alternate base rate. The single financial covenant in the 2018 Credit Facility requires that total debt not exceed 65% of total capitalization as of the last day of each fiscal quarter of the Company. The 2018 Credit Facility expires in February 2023.

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Taxes

The following table sets forth selected data with respect to the Company’s income tax provisions for the years ended December 31, (in millions):



	2017			2016			2015
Income before income taxes:
United States	$	354.7		$	349.5		$	347.2
International	88.4			80.9			71.4
TOTAL INCOME BEFORE INCOME TAXES	$	443.1		$	430.4		$	418.6
Provision for income taxes — current:
Federal	$	164.1		$	85.5		$	110.4
State	15.3			17.4			13.7
International	28.1			17.0			17.6
Total provision — current	207.5			119.9			141.7
Provision for income taxes — deferred:
Federal	(10.4		)	13.5			(1.7		)
State	(0.9		)	1.3			0.4
International	(3.0		)	(2.1		)	(3.9		)
Total provision — deferred	(14.3		)	12.7			(5.2		)
TOTAL PROVISION FOR INCOME TAXES	$	193.2		$	132.6		$	136.5

On December 22, 2017, the TCJA was enacted into law, reducing the Federal corporate income tax rate from 35% to 21%. The provisions of the TCJA have and will continue to impact our accounting treatment of certain items in our financial statements. As of December 31, 2017, we have not completed our assessment of the accounting impact of the tax effects of enactment of the TCJA and accordingly our accounting is provisional as of and for the year ended December 31, 2017. Where we have been able to make a reasonable estimate of the impact, we have accounted for such provisional impact in the accompanying 2017 financial statements. In other cases, we have not yet been able to determine a reasonable estimate and continue to account for those items based on our existing accounting under ASC 740, Income Taxes, and the provisions of the tax laws that were in effect immediately prior to enactment of the TCJA. For items related to the TCJA for which we were able to determine a reasonable estimate, we recognized a provisional tax amount of approximately $57 million, which is included as a component of income tax expense from continuing operations.

The TCJA is complex and includes significant changes to the Internal Revenue Code which impact the Company. To complete the accounting associated with the TCJA, the Company will continue to review the technical tax interpretations associated with the underlying law, monitor state legislative changes, and review U.S. federal and state guidance as it is issued. Further, the Company will continue to accumulate and refine the relevant data and computational elements needed to finalize its accounting during the measurement period.

While the provisions of the TCJA are generally effective January 1, 2018, several provisions impact the Company’s current period financial statements.

Our 2017 accompanying financial statements reflect provisional estimates for the one-time transition tax on the untaxed post-1986 earning and profits ("E&P") of our foreign subsidiaries. In addition, we revalued our deferred tax assets and liabilities based on rates at which they are expected to reverse in the future, which is generally 21%.

Prior to the enactment of the TCJA, the Company had not provided for taxes on the undistributed earnings of its foreign subsidiaries as the Company either reinvested or intended to reinvest those earnings outside of the United States. As of December 31, 2017, the Company had subsidiaries in 17 countries outside the U.S. However, as a result of the TCJA, the Company plans to repatriate a portion of its foreign earnings and has included a provisional tax amount in the accompanying financial statements related to certain of our outside basis differences. As of December 31, 2017, the remaining undistributed foreign earnings were approximately $720 million. We have not included a provisional amount for the income tax effects of a repatriation of this balance because we have not determined a reasonable estimate related to it.

The Company also evaluated the impact of the TCJA on its uncertain tax positions as well as its state and foreign tax liabilities and recorded provisional estimates of these impacts.

Deferred Taxes

With respect to our deferred taxes, we have made provisional estimates on amounts impacted by the TCJA but we are still analyzing certain aspects of the TCJA and refining our calculation, which could potentially affect the measurement of these balances or potentially give rise to new deferred tax amounts. As the Company continues to monitor and evaluate the external regulatory guidance impacting our provisional amounts, the Company will also obtain, prepare and analyze additional information to further refine our provisional estimate for deferred taxes.

Transition Tax and Unremitted Foreign Earnings

Our provisional accounting for the transition tax is based on our estimate of both E&P and the portion of E&P which is held in cash and other specified assets measured as of specific dates. This transition tax charge will be updated throughout the measurement period as we finalize our calculations of E&P and the amounts held in cash or other specified assets, relative to the date such assets are required to be measured.

The provisional amount recorded with respect to a portion of our previously unremitted foreign earnings reflects our estimate of the taxes that would be payable taking into consideration the impact of the TCJA on certain of our outside basis differences. No additional income taxes have been provided for any remaining undistributed earnings not subject to the transition tax at this time. As the Company continues to monitor and evaluate the external regulatory guidance impacting our provisional amounts, the Company will also obtain, prepare and analyze additional information to further refine our provisional estimate for the transition tax and to determine whether an additional provisional amount is required with respect to the remaining unremitted foreign earnings of our foreign subsidiaries. This information includes, but is not limited to, U.S. Federal income attributes, U.S. State income/franchise tax analysis and developments, non-U.S. income and withholding tax obligations on any actual repatriation actions, non-U.S. legal and regulatory restrictions related to capital, availability and utilization of U.S. and non-U.S. tax attributes and impacts on current and deferred taxes due to the TCJA.

Deferred tax assets and liabilities result from differences in the basis of assets and liabilities for tax and financial statement purposes. The components of the deferred tax assets/(liabilities) at December 31, were as follows (in millions):



	2017			2016
Deferred tax assets:
Inventories	$	5.2		$	8.8
Income tax credits	21.0			30.9
Accrued liabilities	17.2			20.8
Pension	55.8			77.6
Post retirement and post employment benefits	6.5			10.0
Stock-based compensation	13.4			17.5
Net operating loss carryforwards	19.0			27.2
Miscellaneous other	10.7			7.5
Gross deferred tax assets	148.8			200.3
Valuation allowance	(19.4		)	(22.6		)
Total deferred tax assets, net of valuation allowance	129.4			177.7
Deferred tax liabilities:
Acquisition basis difference	(116.5		)	(162.1		)
Property, plant, and equipment	(30.3		)	(46.3		)
Total deferred tax liabilities	(146.8		)	(208.4		)
TOTAL NET DEFERRED TAX LIABILITY	$	(17.4	)	$	(30.7	)
Deferred taxes are reflected in the Consolidated Balance Sheet as follows:
Non-current tax assets (included in Other long-term assets)	6.3			10.5
Non-current tax liabilities (included in Other Non-Current Liabilities)	(23.7		)	(41.2		)
TOTAL NET DEFERRED TAX LIABILITY	$	(17.4	)	$	(30.7	)

As of December 31, 2017, the Company had a total of $21.0 million of Federal, State (net of Federal benefit) and foreign tax credit carryforwards, available to offset future income taxes. As of December 31, 2017, $12.7 million of the tax credits may be carried forward indefinitely while the remaining $8.3 million will begin to expire at various times in 2018 through 2036. As of December 31, 2017, the Company had recorded tax benefits totaling $19.0 million for Federal, State and foreign net operating loss carryforwards (“NOLs”). As of December 31, 2017, $9.1 million of NOLs may be carried forward indefinitely while the remaining $9.9 million will begin to expire at various times in 2020 through 2029. The tax benefit related to a portion of these NOLs has been adjusted to reflect an “ownership change” pursuant to Internal Revenue Code Section 382, which imposes an annual limitation on the utilization of pre-acquisition operating losses. The Company has recorded a net valuation allowance of $19.4 million for the portion of the foreign tax and state tax credit carryforwards, capital loss carryforwards and foreign NOLs that the Company anticipates will expire prior to utilization. In addition, the provisional impacts of the TCJA have been recorded on certain credit carryforwards and related valuation allowances.

Cash payments of income taxes were $130.8 million, $117.4 million and $139.1 million in 2017, 2016, and 2015, respectively.

The Company operates within multiple taxing jurisdictions and is subject to audit in these jurisdictions. The IRS and other tax authorities routinely audit the Company’s tax returns. These audits can involve complex issues which may require an extended period of time to resolve. During 2017 the IRS completed an examination of the Company’s 2013 and 2014 Federal income tax returns. The Company is not currently under Federal examination for any open tax year. With few exceptions, the Company is no longer subject to state, local, or non-U.S. income tax examinations by tax authorities for years prior to 2010.

The following tax years, by major jurisdiction, are still subject to examination by taxing authorities:



Jurisdiction	Open Years
United States	2015-2017
UK	2016-2017
Puerto Rico	2013-2017
Canada	2013-2017

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in millions):



	2017			2016			2015
Unrecognized tax benefits at beginning of year	$	20.2		$	20.3		$	21.6
Additions based on tax positions relating to the current year	13.6			2.8			2.9
Reductions based on expiration of statute of limitations	(1.4		)	(5.7		)	(2.8		)
Additions to tax positions relating to previous years	1.0			2.9			0.4
Settlements	(3.9		)	(0.1		)	(1.8		)
TOTAL UNRECOGNIZED TAX BENEFITS	$	29.5		$	20.2		$	20.3

Included in the balance at December 31, 2017 are approximately $15.9 million to $26.1 million of tax positions which, if in the future are determined to be recognizable, would affect the annual effective income tax rate. Additionally, there are $0.9 million of tax positions for which the ultimate deductibility is highly certain but for which there is uncertainty as to the timing of such deductibility. Because of the impact of deferred tax accounting, other than interest and penalties, the disallowance of the shorter deductibility period would not affect the annual effective tax rate but would accelerate the payment of cash to the applicable taxing authority to an earlier period. It is reasonably possible that in the next twelve months, because of changes in facts and circumstances, the unrecognized tax benefits may increase or decrease.

The Company estimates a possible decrease of approximately $1.0 million to $11.8 million within the next twelve months due to the expiration of the statute of limitations, the completion of certain tax audits and technical clarifications associated with the TCJA on various unrecognized tax positions.

The Company’s policy is to record interest and penalties associated with the underpayment of income taxes within Provision for income taxes in the Consolidated Statement of Income. The Company recognized expense, before federal tax impact, related to interest and penalties of approximately $0.5 million in 2017, $0.7 million in 2016 and $1.2 million 2015. The Company had $5.2 million and $4.8 million accrued for the payment of interest and penalties as of December 31, 2017 and December 31, 2016, respectively.

The consolidated effective income tax rate varied from the United States federal statutory income tax rate for the years ended December 31, as follows:



	2017		2016		2015
Federal statutory income tax rate	35.0	%	35.0	%	35.0	%
State income taxes, net of federal benefit	1.2		2.4		2.3
Foreign income taxes	(3.1	)	(3.4	)	(3.9	)
TCJA and related	12.8		—		—
Other, net	(2.3	)	(3.2	)	(0.8	)
CONSOLIDATED EFFECTIVE INCOME TAX RATE	43.6	%	30.8	%	32.6	%

The foreign income tax benefit shown is primarily due to lower statutory rates in foreign jurisdictions compared to the Federal statutory rate. The TCJA and related tax costs include a provisional benefit related to the re-measurement of our net deferred tax liability, provisional tax costs related to the mandatory deemed repatriation and an actual planned repatriation and related tax reserves.

Financial Instruments and Fair Value Measurement

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Financial Instruments and Fair Value Measurement

Financial Instruments

Concentrations of Credit Risk: Financial instruments which potentially subject the Company to significant concentrations of credit risk consist of trade receivables, cash equivalents and investments. The Company grants credit terms in the normal course of business to its customers. Due to the diversity of its product lines, the Company has an extensive customer base including electrical distributors and wholesalers, electric utilities, equipment manufacturers, electrical contractors, telecommunication companies and retail and hardware outlets. No single customer accounted for more than 10% of total sales in any year during the three years ended December 31, 2017. However, the Company’s top ten customers account for approximately 40% of its net sales. As part of its ongoing procedures, the Company monitors the credit worthiness of its customers. Bad debt write-offs have historically been minimal. The Company places its cash and cash equivalents with financial institutions and limits the amount of exposure in any one institution.

Fair Value: The carrying amounts reported in the Consolidated Balance Sheet for cash and cash equivalents, short-term investments, receivables, bank borrowings, accounts payable and accruals approximate their fair values given the immediate or short-term nature of these items. See also Note 6 — Investments.

Fair value measurements

At December 31, 2017 and 2016 the Company had $72.2 million and $67.6 million respectively, of investments carried on the balance sheet at fair value. Fair value is defined as the amount that would be received for selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The FASB fair value measurement guidance established a fair value hierarchy that prioritizes the inputs used to measure fair value. Refer to Note 6 — Investments for more information about these investments.

The three broad levels of the fair value hierarchy are as follows:


Level 1 -	Quoted prices (unadjusted) in active markets for identical assets or liabilities


Level 2 -	Quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly


Level 3 -	Unobservable inputs for which little or no market data exists, therefore requiring a company to develop its own assumptions

The following tables show, by level within the fair value hierarchy, the Company’s financial assets and liabilities that are accounted for at fair value on a recurring basis at December 31, 2017 and 2016 (in millions):



Asset (Liability)	Quoted Prices in Active Markets for Identical Assets (Level 1)			Quoted Prices in Active Markets for Similar Assets (Level 2)			Unobservable inputs for which little or no market data exists (Level 3)		Total
Money market funds^(a)	$	126.9		$	—		$	—	$	126.9
Available for sale investments	—			54.3			4.1		58.4
Trading securities	13.8			—			—		13.8
Deferred compensation plan liabilities	(13.8		)	—			—		(13.8		)
Derivatives:
Forward exchange contracts-Assets^(b)	—			0.2			—		0.2
Forward exchange contracts-(Liabilities)^(c)	—			(0.7		)	—		(0.7		)
BALANCE AT DECEMBER 31, 2017	$	126.9		$	53.8		$	4.1	$	184.8



Asset (Liability)	Quoted Prices in Active Markets for Identical Assets (Level 1)			Quoted Prices in Active Markets for Similar Assets (Level 2)			Unobservable inputs for which little or no market data exists (Level 3)		Total
Money market funds ^(a)	$	263.5		$	—		$	—	$	263.5
Available-for-sale investments	—			53.6			3.8		57.4
Trading securities	10.2			—			—		10.2
Deferred compensation plan liabilities	(10.2		)	—			—		(10.2		)
Derivatives:
Forward exchange contracts-Assets^(b)	—			0.8			—		0.8
Forward exchange contracts-(Liabilities)^(c)	—			(0.1		)	—		(0.1		)
BALANCE AT DECEMBER 31, 2016	$	263.5		$	54.3		$	3.8	$	321.6


(a)	Money market funds are included in Cash and cash equivalents in the Consolidated Balance Sheet.


(b)	Forward exchange contracts-Assets are reflected in Other current assets in the Consolidated Balance Sheet.


(c)	Forward exchange contracts-(Liabilities) are reflected in Other accrued liabilities in the Consolidated Balance Sheet.

The methods and assumptions used to estimate the Level 2 fair values were as follows:

Forward exchange contracts – The fair value of forward exchange contracts were based on quoted forward foreign exchange prices at the reporting date.

Municipal bonds – The fair value of available-for-sale investments in municipal bonds is based on observable market-based inputs, other than quoted prices in active markets for identical assets.

Available-for-sale redeemable preferred stock classified in Level 3 – The fair value of the available-for-sale investment in redeemable preferred stock is valued based on a discounted cash flow model, using significant unobservable inputs, including assumptions regarding expected cash flows and discount rates.

During 2017 and 2016, there were no transfers of financial assets or liabilities in or out of Level 1 or Level 2 of the fair value hierarchy. As of December 31, 2017 and 2016, the Company had one financial asset that was classified in Level 3 of the fair value hierarchy.

Deferred compensation plan

The Company offers certain employees the opportunity to participate in non-qualified deferred compensation plans. A participant’s deferrals are invested in a variety of participant-directed debt and equity mutual funds that are classified as trading securities. During 2017 and 2016, the Company purchased $2.1 million and $1.4 million, respectively, of trading securities related to these deferred compensation plans. As a result of participant distributions, the Company sold $0.3 million and $1.6 million of these trading securities in 2017 and 2016 respectively. The unrealized gains and losses associated with these trading securities are directly offset by the changes in the fair value of the underlying deferred compensation plan obligation.

Derivatives

In order to limit financial risk in the management of its assets, liabilities and debt, the Company may use derivative financial instruments such as foreign currency hedges, commodity hedges, interest rate hedges and interest rate swaps. All derivative financial instruments are matched with an existing Company asset, liability or proposed transaction. Market value gains or losses on the derivative financial instrument are recognized in income when the effects of the related price changes of the underlying asset or liability are recognized in income.

Forward exchange contracts

In 2017 and 2016, the Company entered into a series of forward exchange contracts to purchase U.S. dollars in order to hedge its exposure to fluctuating rates of exchange on anticipated inventory purchases and forecasted sales by its subsidiaries who transact business in Canadian dollars. As of December 31, 2017, the Company had 46 individual forward exchange contracts for notional amounts which range from $0.4 million to $1.5 million each, which have various expiration dates through December 2018. These contracts have been designated as cash flow hedges in accordance with the accounting guidance for derivatives.

The following table summarizes the results of cash flow hedging relationships for years ended December 31, (in millions):



	Derivative Gain/(Loss) Recognized in Accumulated Other Comprehensive Loss, net of tax						Location of Gain/(Loss) when reclassified	Gain/(Loss) Reclassified into Earnings (Effective Portion), net of tax
Derivative Instrument	2017			2016			(Effective Portion)	2017			2016
Forward exchange contract	$	(1.7	)	$	(1.4	)	Net sales	$	(0.3	)	$	(0.3	)
							Cost of goods sold	$	(0.6	)	$	0.3

There was no material hedge ineffectiveness with respect to the forward exchange cash flow hedges during 2017, 2016 and 2015.

Long-term Debt

The total carrying value of long-term debt as of December 31, 2017 and 2016 was $987.1 million and $990.5 million, respectively, net of unamortized discount and debt issuance costs. As of December 31, 2017 and 2016, the estimated fair value of the long-term debt was $1,013.2 million and $1,017.8 million, respectively, based on quoted market prices. The Company’s long-term debt falls within level 2 of the fair value hierarchy.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Commitments and Contingencies

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Legal and Environmental

The Company is subject to various legal proceedings arising in the normal course of its business. These proceedings include claims for damages arising out of use of the Company’s products, intellectual property, workers’ compensation and environmental matters. The Company is self-insured up to specified limits for certain types of claims, including product liability and workers’ compensation, and is fully self-insured for certain other types of claims, including environmental and intellectual property matters. The Company recognizes a liability for any contingency that in management’s judgment is probable of occurrence and can be reasonably estimated. We continually reassess the likelihood of adverse judgments and outcomes in these matters, as well as estimated ranges of possible losses based upon an analysis of each matter which includes consideration of outside legal counsel and, if applicable, other experts.

The Company is subject to environmental laws and regulations which may require that it investigate and remediate the effects of potential contamination associated with past and present operations as well as those acquired through business combinations. Environmental liabilities are recorded when remedial efforts are probable and the costs can be reasonably estimated. The Company continues to monitor these environmental matters and revalues its liabilities as necessary. Total environmental liabilities were $4.9 million and $5.2 million as of December 31, 2017 and 2016, respectively.

The Company accounts for conditional asset retirement and environmental obligations in accordance with the applicable accounting guidance. The accounting guidance defines “conditional asset retirement obligation” as a legal obligation to perform an asset retirement activity in which the timing and/or method of settlement are conditional on a future event that may or may not be within the control of the Company. Accordingly, an entity is required to recognize a liability for the fair value of a conditional asset retirement obligation if the fair value of the liability can be reasonably estimated. Asset retirement obligations were not material as of December 31, 2017 and 2016.

Leases

Total rental expense under operating leases was $30.5 million in 2017, $28.8 million in 2016 and $25.7 million in 2015. The minimum annual rentals on non-cancelable, long-term, operating leases in effect at December 31, 2017 are expected to approximate $18.0 million in 2018, $15.6 million in 2019, $10.8 million in 2020, $8.2 million in 2021, $6.2 million in 2022 and $18.8 million thereafter. The Company’s leases primarily consist of operating leases for buildings or equipment. The terms for building leases typically range from month-to-month to up to 11 years, with various renewal periods depending on the terms.

Capital Stock

12 Months Ended

Dec. 31, 2017

Stockholders' Equity Note [Abstract]

Capital Stock

Activity in the Company’s common shares outstanding is set forth below for the three years ended December 31, 2017 (in thousands):



	Common Stock
	Class A		Class B		Common Stock
OUTSTANDING AT DECEMBER 31, 2014	7,167		51,329		—
Exercise of stock options/stock appreciation rights	—		29		—
Director compensation arrangements, net	—		17		—
Restricted/performance shares activity, net of forfeitures	—		122		—
Acquisition/surrender of shares	—		(708	)	(119	)
Share reclassification	(7,167	)	(50,789	)	57,956
OUTSTANDING AT DECEMBER 31, 2015	—		—		57,837
Exercise of stock appreciation rights	—		—		78
Director compensation arrangements, net	—		—		6
Restricted/performance shares activity, net of forfeitures	—		—		98
Acquisition/surrender of shares	—		—		(2,487	)
OUTSTANDING AT DECEMBER 31, 2016	—		—		55,532
Exercise of stock appreciation rights	—		—		53
Director compensation arrangements, net	—		—		10
Restricted/performance shares activity, net of forfeitures	—		—		89
Acquisition/surrender of shares	—		—		(802	)
OUTSTANDING AT DECEMBER 31, 2017	—		—		54,882

On December 23, 2015, the Company completed the reclassification of its dual-class common stock into a single class of Common Stock (the “Reclassification”).

The Reclassification, among other benefits, simplified the Company's capital structure, better aligned voting rights with economic interests of all shareholders, and has eliminated the ability of the Louie E. Roche Trust and the Harvey Hubbell Trust (collectively, the “Trusts”), which, prior to the Reclassification, collectively owned 3,488,460 shares of the Company’s Class A common stock, par value $0.01 per share (the “Class A common stock”), representing approximately 49% of Class A common stock then outstanding, and approximately 36% of the total voting power of the Company's shareholders, to effectively prevent the approval of any matter that comes before the shareholders that requires, under Connecticut law, the approval of holders of two-thirds of the Company's outstanding common stock.

Following the filing of the Amended and Restated Certificate of Incorporation of the Company with the Secretary of the State of the State of Connecticut, the Reclassification became effective at 11:59 p.m. on December 23, 2015 (the “Effective Time”), at which time (i) each holder of Class A common stock as of immediately prior to the Effective Time became entitled to receive cash in the amount of $28.00 for each share of Class A common stock held ("Class A Cash Consideration") and (ii) each share of Class A common stock issued and outstanding immediately prior to the Effective Time and each share of Class B common stock of the Company, par value $0.01 per share (the “Class B common stock”), issued and outstanding immediately prior to the Effective Time was reclassified into one share of common stock of the Company, par value $0.01 per share and having one vote per share upon all matters brought before any meeting of the shareholders (the “Common Stock”). Trading in the Class A Common Stock and Class B Common Stock ceased after markets closed on December 23, 2015 and trading in the Company's single class of Common Stock commenced on the NYSE on December 24, 2015, under the ticker “HUBB.”

Prior to the Reclassification, shares of Class A common stock had twenty votes per share, while shares of Class B common shares had one vote per share. Following the Reclassification, shares of the Company's Common Stock have one vote per share.

The Company accounted for the Reclassification by adjusting the Company’s capital stock accounts. The par value of the Class A common stock and the Class B common stock was reclassified to Common Stock par value. Paid-in capital of the Class A Common Stock was zero at the time of the Reclassification and, therefore, the full amount of the Class A Cash Consideration paid in the Reclassification was applied as a reduction to Retained earnings for the fiscal year ended December 31, 2015.

For accounting purposes, the Company treats repurchased shares as constructively retired when acquired and accordingly charges the purchase price against Common Stock par value, Additional paid-in capital and Retained earnings to the extent required. Shares may be repurchased through the Company’s stock repurchase program, acquired by the Company from employees under the Hubbell Incorporated Stock Option Plan for Key Employees (the “Option Plan”) or surrendered to the Company by employees in settlement of their minimum tax liability on vesting of restricted shares and performance shares under the Hubbell Incorporated 2005 Incentive Award Plan as amended and restated, (the “Award Plan”).

In connection with the completion of the Reclassification, the Company entered into a Second Amended and Restated Rights Agreement, dated December 23, 2015 (the "Rights Agreement"), between the Company and Computershare Inc. (successor to Mellon Investor Services, L.L.C.), as rights agent, under which holders of Common Stock had a preferred share purchase right for each share of Common Stock (the “Rights”). The Rights expired at the close of business on December 17, 2016 and the Rights Agreement is no longer in effect.

Shares of the Company’s common stock were reserved at December 31, 2017 as follows (in thousands):



	Common Stock
	Common Stock
Future grant of stock-based compensation	2,609
Shares reserved under other equity compensation plans	161
TOTAL	2,770

Stock-Based Compensation

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

As of December 31, 2017, the Company had various stock-based awards outstanding which were issued to executives and other key employees. The Company recognizes the grant-date fair value of all stock-based awards to employees over their respective requisite service periods (generally equal to an award’s vesting period), net of estimated forfeitures. A stock-based award is considered vested for expense attribution purposes when the employee’s retention of the award is no longer contingent on providing subsequent service. Accordingly, the Company generally recognizes compensation cost immediately for awards granted to retirement-eligible individuals or over the period from the grant date to the date retirement eligibility is achieved, if less than the stated vesting period.

The Company’s long-term incentive program for awarding stock-based compensation uses a combination of restricted stock, stock appreciation rights (“SARs”), and performance shares of the Company’s Common Stock pursuant to the Award Plan. The Award Plan was amended and restated during 2015 to add an additional 2.8 million shares. Under the Award Plan, the Company may authorize up to 9.7 million shares of Common Stock in settlement of restricted stock, performance shares, SARs or any-post 2004 grants of stock options. The Company issues new shares for settlement of any stock-based awards. In 2017, the Company granted stock-based awards using a combination of restricted stock, SARs and performance shares.

On December 23, 2015, the Company completed the reclassification of its dual-class common stock into a single class of Common Stock (the “Reclassification”), as more fully described in Note 15 — Capital Stock. At the effective time of the Reclassification, each outstanding stock-based award granted under the Award Plan was adjusted by substituting, on a one for one basis, shares of Common Stock for shares the of Class B Common Stock granted under the Award Plan.

Stock-based compensation expense recognized by the Company was $22.3 million in 2017 and 2016, and was $17.0 million in 2015. The total income tax benefit recognized in 2017 was $5.4 million including the impact of the TCJA, $8.2 million during 2016, and $6.2 million during 2015. The net tax windfall recorded as a result of exercise or vesting (depending on the type of award) was $2.5 million, $3.7 million, and $0.9 million for the years ended December 31, 2017, 2016 and 2015, respectively. As of December 31, 2017, there was $31.1 million, pretax, of total unrecognized compensation cost related to non-vested share-based compensation arrangements. This cost is expected to be recognized through 2020.

Stock-based compensation expense is recorded in S&A expense as well as Cost of goods sold. Of the total 2017 expense, $21.1 million was recorded to S&A expense and $1.2 million was recorded to Cost of goods sold. In 2016 and 2015, $21.6 million and $16.2 million, respectively, was recorded to S&A expense and $0.7 million in 2016 and $0.8 million in 2015, was recorded to Cost of goods sold. Stock-based compensation costs capitalized to inventory was $0.3 million in 2017, and $0.2 million in 2016 and 2015.

Each of the compensation arrangements is discussed below.

Restricted Stock

The Company issues several types of restricted stock awards all of which are considered outstanding at the time of grant, as the award holders are entitled to dividends and voting rights. Unvested restricted stock awards are considered participating securities in computing earnings per share. Restricted stock granted is not transferable and is subject to forfeiture in the event of the recipient’s termination of employment prior to vesting.

Restricted Stock Issued to Employees - Service Condition

Service-based restricted stock awards are expensed on a straight-line basis over the requisite service period. The restricted stock vests in one-third increments annually for three years on each anniversary of the date of grant. The restricted stock fair values are measured using the average of the high and low trading prices of the Company’s common stock on the most recent trading day immediately preceding the grant date (“measurement date”).

Restricted Stock Issued to Employees - Market Condition

Certain restricted stock awards issued in 2015, 2016 and 2017 will vest subject to the achievement of a market-based condition. The awards are expensed on a straight-line basis over the requisite service period which starts on the date of the grant and ends upon the completion of the performance period. Expense is recognized irrespective of the market condition being achieved.

The market-based condition is the Company’s total shareholder return (“TSR”) compared to the TSR generated by the companies that comprise the S&P Capital Goods 900 Index and is measured over a three year performance period beginning on January 1st of the first year and ending on December 31st of the third year. The awards will vest contingent upon achievement of the market condition, service through the requisite service period or the retirement-eligibility date. If the market-based condition is achieved, the awards will vest at 100% of the restricted stock awards granted. If the market-based condition is not achieved the awards will not vest. The fair value of these awards was determined based upon a lattice model.

The performance condition for year ending December 31, 2017 was met and 23,280 shares vested and were approved by the Compensation Committee in February 2018. The fair value of the shares at vesting was $3.1 million.

The following table summarizes the assumptions used in estimating the fair value of these awards:



Grant Date	Stock Price on Measurement Date		Expected Volatility		Risk Free Interest Rate		Expected Term	Weighted Avg. Grant Date Fair Value
2017	$	127.51	24.7	%	1.9	%	3 Years	$	119.88
2016	$	113.69	25.6	%	1.4	%	3 Years	$	104.93
2015	$	97.48	23.3	%	1.3	%	3 Years	$	87.61

Restricted Stock Issued to Non-employee Directors

In 2017, 2016 and 2015, each non-employee director received a restricted stock grant. These grants were made on the date of the annual meeting of shareholders and vested or will vest at the following year’s annual meeting of shareholders, upon a change of control or termination of service by reason of death. These shares will be subject to forfeiture if the director’s service terminates prior to the date of the next regularly scheduled annual meeting of shareholders to be held in the following calendar year. During the years 2017, 2016 and 2015, the Company issued to non-employee directors 8,480 shares, 9,128 shares, and 8,008 shares, respectively.

Activity related to both employee and non-employee restricted stock for the year ended December 31, 2017 is as follows (in thousands, except per share amounts):



	Shares		Weighted Average Grant Date Fair Value/Share
RESTRICTED STOCK AT DECEMBER 31, 2016	224		$	102.37
Shares granted	81		123.39
Shares vested	(62	)	106.06
Shares forfeited	(4	)	104.54
RESTRICTED STOCK AT DECEMBER 31, 2017	239		$	108.51

The weighted average fair value per share of restricted stock granted during the years 2017, 2016 and 2015 was $123.39, $109.95 and $96.26, respectively. The total fair value of restricted stock vested during the years 2017, 2016 and 2015 was $6.6 million, $6.4 million and $7.7 million, respectively.

Stock Appreciation Rights

SARs granted entitle the recipient to the difference between the fair market value of the Company’s Common Stock on the date of exercise and the grant price as determined using the average of the high and the low trading prices of the Company’s common stock on the measurement date. This amount is payable in shares of the Company’s Common Stock. SARs vest and become exercisable in three equal installments during the first three years following their grant date and expire ten years from the grant date.

Activity related to SARs for the year ended December 31, 2017 is as follows (in thousands, except per share amounts):



	Number of Rights		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value
OUTSTANDING AT DECEMBER 31, 2016	1,811		$	94.51
Granted	432		127.28
Exercised	(191	)	70.78
Forfeited	(9	)	107.39
Canceled	(1	)	97.48
OUTSTANDING AT DECEMBER 31, 2017	2,042		$	103.59	7.4 Years	$	64,841
EXERCISABLE AT DECEMBER 31, 2017	1,241		$	93.89	6.2 Years	$	51,420

The aggregated intrinsic value of SARs exercised during 2017, 2016 and 2015 was $10.1 million, $13.8 million and $4.8 million, respectively.

The fair value of each SAR award was measured using the Black-Scholes option pricing model.

The following table summarizes the weighted-average assumptions used in estimating the fair value of the SARs granted during the years 2017, 2016 and 2015:



Grant Date	Expected Dividend Yield		Expected Volatility		Risk Free Interest Rate		Expected Term	Weighted Avg. Grant Date Fair Value of 1 SAR
2017	2.6	%	18.0	%	2.2	%	5.5 Years	$	17.45
2016	2.6	%	22.3	%	1.9	%	5.5 Years	$	18.76
2015	2.7	%	22.7	%	1.7	%	5.5 Years	$	16.05

The expected dividend yield was calculated by dividing the Company’s expected annual dividend by the average stock price for the past three months. Expected volatilities are based on historical volatilities of the Company’s stock for a period consistent with the expected term. The expected term of SARs granted was based upon historical exercise behavior of stock options and SARs. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant for the expected term of the award.

Performance Shares

Performance shares represent the right to receive a share of the Company’s Common Stock after a three year period subject to the achievement of certain market or performance conditions established by the Company’s Compensation Committee. Partial vesting in these awards may occur after separation from the Company for retirement eligible employees. Shares are not vested until approved by the Company’s Compensation Committee.

Performance Shares - Market Condition

In December 2017, 2016 and 2015, the Company granted 24,675, 29,012 and 32,687, respectively, of performance shares that will vest subject to a market condition and service through the performance period. The market condition associated with the awards is the Company's TSR compared to the TSR generated by the companies of a reference index over a three year performance period. Performance at target will result in vesting and issuance of the number of performance shares granted, equal to 100% payout. Performance below or above target can result in issuance in the range of 0%-200% of the number of shares granted. Expense is recognized irrespective of the market condition being achieved.

In February 2018, the Company paid out 15,141 shares related to the December 2014 performance award grant. The performance period associated with this award was from January 1, 2015 through December 31, 2017 and was based upon the Company’s TSR compared to the TSR generated by the other companies that comprise the S&P Capital Goods 900 Index. The number of shares vested in February 2018 was based upon achieving 64% of the market-based criteria and the fair value of the awards at vesting was $2.0 million.

The fair value of the performance share awards with a market condition for the fiscal years 2017, 2016 and 2015 was determined based upon a lattice model.

The following table summarizes the related assumptions used to determine the fair values of the performance share awards with a market condition granted during the years 2017, 2016 and 2015:



Grant Date	Stock Price on Measurement Date		Dividend Yield		Expected Volatility		Risk Free Interest Rate		Expected Term	Weighted Avg. Grant Date Fair Value
2017	$	127.51	2.4	%	24.7	%	1.9	%	3 Years	$	142.89
2016	$	113.69	2.5	%	25.6	%	1.4	%	3 Years	$	126.65
2015	$	97.48	2.6	%	23.3	%	1.3	%	3 Years	$	105.77

Expected volatilities are based on historical volatilities of the Company’s stock over a three year period. The risk free interest rate is based on the U.S. Treasury yield curve in effect at the time of the grant for the expected term of the award.

Performance Shares - Performance Condition

In December 2017, 2016 and 2015 the Company granted 24,675, 29,012 and 32,687, respectively, of performance share awards that are subject to a performance condition and service requirement during the three year performance period. The performance condition associated with the awards is based on the Company's net sales growth compared to the net sales growth of the companies of a reference index, further adjusted by the Company achieving a target net income margin, each measured over the same three year performance period. Performance at target will result in vesting and issuance of the number of performance shares granted, equal to 100% payout. Performance below or above target can result in issuance in the range of 0%-250% of the number of shares granted.

The fair value of the award is measured based upon the average of the high and low trading prices of the Company's common stock on the measurement date reduced by the present value of dividends expected to be paid during the requisite service period. The Company expenses these awards on a straight-line basis over the requisite service period and including an assessment of the performance achieved to date. The weighted average fair value per share was $118.55 for the awards granted in 2017.

The following table summarizes the attributes of the performance shares outstanding at December 31, 2017:



Grant Date	Shares Outstanding at 12/31/2017	Fair Value	Performance Period	Payout Range
2017	24,675	118.55	Jan 2018-Dec 2020	0-250%
2016	28,524	105.48	Jan 2017-Dec 2019	0-250%
2015	31,024	97.48	Jan 2016-Dec 2018	0-250%
2014	23,688	106.44	Jan 2015-Dec 2017	0-250%

Earnings Per Share

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Earnings Per Share

The Company computes earnings per share using the two-class method, which is an earnings allocation formula that determines earnings per share for common stock and participating securities. Restricted stock granted by the Company is considered a participating security since it contains a non-forfeitable right to dividends.

The following table sets forth the computation of earnings per share for the three years ended December 31 (in millions, except per share amounts):



	2017			2016			2015
Numerator:
Net income attributable to Hubbell	$	243.1		$	293.0		$	277.3
Less: Earnings allocated to participating securities	(0.8		)	(0.9		)	(0.7		)
Net income available to common shareholders	$	242.3		$	292.1		$	276.6
Denominator:
Average number of common shares outstanding	54.8			55.5			57.7
Potential dilutive shares	0.3			0.2			0.3
Average number of diluted shares outstanding	55.1			55.7			58.0
Earnings per share:
Basic	$	4.42		$	5.26		$	4.79
Diluted	$	4.39		$	5.24		$	4.77

The Company did not have any significant anti-dilutive securities in 2017, 2016 or 2015.

Accumulated Other Comprehensive Loss

12 Months Ended

Dec. 31, 2017

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Accumulated Other Comprehensive Loss

A summary of the changes in Accumulated other comprehensive loss (net of tax) for the three years ended December 31, 2017 is provided below (in millions):



(Debit) credit	Cash Flow Hedge (Loss) Gain			Unrealized Gain (Loss) on Available-for-Sale Securities			Pension and Post Retirement Benefit Plan Adjustment			Cumulative Translation Adjustment			Total
BALANCE AT DECEMBER 31, 2014	$	—		$	0.3		$	(124.7	)	$	(39.9	)	$	(164.3	)
Other comprehensive income (loss) before Reclassifications	1.7			(0.3		)	(22.5		)	(45.5		)	(66.6		)
Amounts reclassified from accumulated other comprehensive loss	(0.3		)	—			7.0			—			6.7
Current period other comprehensive income (loss)	1.4			(0.3		)	(15.5		)	(45.5		)	(59.9		)
BALANCE AT DECEMBER 31, 2015	$	1.4		$	—		$	(140.2	)	$	(85.4	)	$	(224.2	)
Other comprehensive income (loss) before Reclassifications	(1.4		)	(1.2		)	(48.5		)	(35.4		)	(86.5		)
Amounts reclassified from accumulated other comprehensive loss	—			—			8.2			—			8.2
Current period other comprehensive income (loss)	(1.4		)	(1.2		)	(40.3		)	(35.4		)	(78.3		)
BALANCE AT DECEMBER 31, 2016	$	—		$	(1.2	)	$	(180.5	)	$	(120.8	)	$	(302.5	)
Other comprehensive income (loss) before Reclassifications	(1.7		)	0.6			(3.4		)	28.9			24.4
Amounts reclassified from accumulated other comprehensive loss	0.9			—			7.4			—			8.3
Current period other comprehensive income (loss)	(0.8		)	0.6			4.0			28.9			32.7
BALANCE AT DECEMBER 31, 2017	$	(0.8	)	$	(0.6	)	$	(176.5	)	$	(91.9	)	$	(269.8	)

A summary of the gain (loss) reclassifications out of Accumulated other comprehensive loss for the two years ended December 31 is provided below (in millions):



Details about Accumulated Other Comprehensive Loss Components	2017				2016				Location of Gain (Loss) Reclassified into Income
Cash flow hedges gain (loss):
Forward exchange contracts	$	(0.4	)		$	(0.3	)		Net Sales
	(0.9		)		0.3				Cost of goods sold
	(1.3		)		—				Total before tax
	0.4				—				Tax (expense) benefit
	$	(0.9	)		$	—			Gain (loss) net of tax
Amortization of defined benefit pension and post retirement benefit items:
Prior-service costs	$	0.9		^(a)	$	0.9		^(a)
Actuarial gains/(losses)	(11.4		)	^(a)	(13.9		)	^(a)
Settlement and curtailment losses	(0.4		)	^(a)	—			^(a)
	(10.9		)		(13.0		)		Total before tax
	3.5				4.8				Tax benefit (expense)
	$	(7.4	)		$	(8.2	)		(Loss) gain net of tax
Losses reclassified into earnings	$	(8.3	)		$	(8.2	)		(Loss) gain net of tax


(a)	These accumulated other comprehensive loss components are included in the computation of net periodic pension cost (see Note 10 — Retirement Benefits for additional details).

Industry Segments and Geographic Area Information

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Industry Segments and Geographic Area Information

Nature of Operations

Hubbell Incorporated was founded as a proprietorship in 1888, and was incorporated in Connecticut in 1905. Hubbell designs, manufactures and sells quality electrical and electronic products for a broad range of non-residential and residential construction, industrial and utility applications. Products are either sourced complete, manufactured or assembled by subsidiaries in the United States, Canada, Switzerland, Puerto Rico, China, Mexico, the UK, Brazil, Australia and Ireland. Hubbell also participates in joint ventures in Taiwan and Hong Kong, and maintains offices in Singapore, Italy, China, India, Mexico, South Korea and countries in the Middle East. Each of the above references to manufacturing locations, joint venture participation, and office locations relate to the three year period ending December 31, 2017, prior to the acquisition of Aclara on February 2, 2018.

The Company’s reporting segments consist of the Electrical segment and the Power segment, as described below.

The Electrical segment is comprised of businesses that sell stock and custom products including standard and special application wiring device products, rough-in electrical products, connector and grounding products, lighting fixtures and controls, components and assemblies for the natural gas distribution market and other electrical equipment. The products are typically used in and around industrial, commercial and institutional facilities by electrical contractors, maintenance personnel, electricians, utilities, and telecommunications companies. In addition, certain businesses design and manufacture a variety of high voltage test and measurement equipment, industrial controls and communication systems used in the non-residential and industrial markets. Many of these products are designed such that they can also be used in harsh and hazardous locations where a potential for fire and explosion exists due to the presence of flammable gasses and vapors. Harsh and hazardous products are primarily used in the oil and gas (onshore and offshore) and mining industries. There are also a variety of lighting fixtures, wiring devices and electrical products that have residential and utility applications, including residential products with Internet-of-Things ("IoT") enabled technologies. These products are primarily sold through electrical and industrial distributors, home centers, retail and hardware outlets, lighting showrooms and residential product oriented internet sites. Special application products are primarily sold through wholesale distributors to contractors, industrial customers and OEMs. High voltage products are also sold direct to customers through our sales engineers. The Electrical segment is comprised of three business groups, which have been aggregated as they have similar economic characteristics, customers and distribution channels, among other factors.

The Power segment consists of operations that design and manufacture various distribution, transmission, substation and telecommunications products primarily used by the electrical utility industry. In addition, certain of these products are used in the civil construction and transportation industries. Products are sold to distributors and directly to users such as utilities, telecommunication companies, pipeline and mining operations, industrial firms, construction and engineering firms. Refer to Note 2 - Business Acquisitions for information regarding the Aclara Acquisition on February 2, 2018 and the products and capabilities that acquisition will add to the Power segment.

Financial Information

Financial information by industry segment, product class and geographic area for each of the three years ended December 31, 2017, 2016 and 2015 is summarized below (in millions). When reading the data the following items should be noted:


•	Net sales comprise sales to unaffiliated customers — inter-segment and inter-area sales are not significant.


•	Segment operating income consists of net sales less operating expenses, including total corporate expenses, which are generally allocated to each segment on the basis of the segment’s percentage of consolidated net sales. Interest expense and investment income and other expense, net have not been allocated to segments as these items are centrally managed by the Company.


•	General corporate assets not allocated to segments are principally cash, prepaid pensions, investments and deferred taxes. These assets have not been allocated as they are centrally managed by the Company.

INDUSTRY SEGMENT DATA



	2017			2016			2015
Net Sales:
Electrical	$	2,532.8		$	2,460.2		$	2,388.3
Power	1,136.0			1,045.0			1,002.1
TOTAL NET SALES	$	3,668.8		$	3,505.2		$	3,390.4
Operating Income:
Electrical	$	282.5		$	267.4		$	279.0
Power	221.2			210.4			195.6
Operating Income	$	503.7		$	477.8		$	474.6
Interest expense	(44.9		)	(43.4		)	(31.0		)
Loss on extinguishment of debt	(10.1		)	—			—
Investment income and other expense, net	(5.6		)	(4.0		)	(25.0		)
INCOME BEFORE INCOME TAXES	$	443.1		$	430.4		$	418.6
Assets:
Electrical	$	2,344.7		$	2,246.0		$	2,120.9
Power	1,102.2			911.5			839.7
General Corporate	273.7			367.5			248.1
TOTAL ASSETS	$	3,720.6		$	3,525.0		$	3,208.7
Capital Expenditures:
Electrical	$	48.0		$	43.4		$	47.9
Power	29.0			22.7			28.4
General Corporate	2.7			1.1			0.8
TOTAL CAPITAL EXPENDITURES	$	79.7		$	67.2		$	77.1
Depreciation and Amortization:
Electrical	$	65.7		$	61.2		$	56.2
Power	34.1			31.1			29.0
TOTAL DEPRECIATION AND AMORTIZATION	$	99.8		$	92.3		$	85.2

PRODUCT CLASS DATA



	2017		2016		2015
Net Sales:
Electrical Systems	$	1,597.1	$	1,514.4	$	1,476.7
Lighting	935.7		945.8		911.6
Power	1,136.0		1,045.0		1,002.1
TOTAL NET SALES	$	3,668.8	$	3,505.2	$	3,390.4

GEOGRAPHIC AREA DATA



	2017		2016		2015
Net Sales:
United States	$	3,280.9	$	3,147.4	$	3,008.4
International	387.9		357.8		382.0
TOTAL NET SALES	$	3,668.8	$	3,505.2	$	3,390.4
Operating Income:
United States	$	422.1	$	419.1	$	426.1
International	81.6		58.7		48.5
TOTAL OPERATING INCOME	$	503.7	$	477.8	$	474.6
Long-lived Assets:
United States	$	1,877.4	$	1,762.9	$	1,627.7
International	232.8		200.1		187.1
TOTAL LONG-LIVED ASSETS	$	2,110.2	$	1,963.0	$	1,814.8

On a geographic basis, the Company defines “international” as operations based outside of the United States and its possessions. As a percentage of total net sales, shipments from foreign operations directly to third parties were 11% in 2017, 10% in 2016 and 11% in 2015, with the Canadian, UK and Brazilian operations representing approximately 31%, 21% and 12% respectively, of 2017 total international net sales.

Long-lived assets, excluding deferred tax assets, of international subsidiaries were 11% of the consolidated total in 2017, 10% in 2016 and 10% in 2015, with the UK, Mexico and Canada operations representing approximately 31%, 19%, and 16%, respectively, of the 2017 international total. Export sales from United States operations were $217.2 million in 2017, $213.8 million in 2016 and $224.9 million in 2015.

Guarantees

12 Months Ended

Dec. 31, 2017

Standard Product Warranty Disclosure [Abstract]

Guarantees

The Company records a liability equal to the fair value of guarantees in the Consolidated Balance Sheet in accordance with the accounting guidance for guarantees. When it is probable that a liability has been incurred and the amount can be reasonably estimated, the Company accrues for costs associated with guarantees. The most likely costs to be incurred are accrued based on an evaluation of currently available facts and, where no amount within a range of estimates is more likely, the minimum is accrued.

As of December 31, 2017, the fair value and maximum potential payment related to the Company’s guarantees were not material.

The Company offers product warranties which cover defects on most of its products. These warranties primarily apply to products that are properly installed, maintained and used for their intended purpose. The Company accrues estimated

warranty costs at the time of sale. Estimated warranty expenses, recorded in cost of goods sold, are based upon historical information such as past experience, product failure rates, or the estimated number of units to be repaired or replaced. Adjustments are made to the product warranty accrual as claims are incurred, additional information becomes known or as historical experience indicates.

Changes in the accrual for product warranties in 2017 are set forth below (in millions):



BALANCE AT DECEMBER 31, 2015	$	13.2
Provision	9.7
Expenditures/other	(9.1		)
BALANCE AT DECEMBER 31, 2016	$	13.8
Provision	10.0
Expenditures/other	(9.8		)
BALANCE AT DECEMBER 31, 2017	$	14.0

Restructuring Costs

12 Months Ended

Dec. 31, 2017

Restructuring and Related Activities [Abstract]

Restructuring Costs

During 2017, we incurred costs for restructuring actions initiated in 2017 as well as costs involving restructuring actions initiated in the prior year. Our restructuring actions are associated with cost reduction efforts that include the consolidation of manufacturing and distribution facilities as well as workforce reductions and the sale or exit of business units we determine to be non-strategic. Restructuring costs are primarily severance and employee benefits, asset impairments, as well as facility closure, contract termination and certain pension costs that are directly related to restructuring actions. These costs are predominantly settled in cash from our operating activities and are generally settled within one year, with the exception of asset impairments, which are non-cash, and a $12.5 million charge in the fourth quarter of 2016 to recognize the estimated liability associated with the withdrawal from a multi-employer pension plan. That withdrawal liability may be settled either in periodic payments over approximately 19 years, or in a lump sum, subject to negotiation.

Pre-tax restructuring costs incurred in each of our segments and the location of the costs in the Consolidated Statement of Income for the years ended December 31, 2017, 2016 and 2015 are as follows (in millions):



Year Ended December 31, 2015	Cost of goods sold		Selling & administrative expense		Total
Electrical Segment	$	14.5	$	7.2	$	21.7
Power Segment	0.8		1.1		1.9
Total 2015 Restructuring Costs	$	15.3	$	8.3	$	23.6

Year Ended December 31, 2016
Electrical Segment	$	27.3	$	6.6	$	33.9
Power Segment	0.2		0.9		1.1
Total 2016 Restructuring Costs	$	27.5	$	7.5	$	35.0

Year Ended December 31, 2017
Electrical Segment	$	11.5	$	5.4	$	16.9
Power Segment	2.2		1.2		3.4
Total 2017 Restructuring Costs	$	13.7	$	6.6	$	20.3

The following table summarizes the accrued liabilities for our restructuring actions (in millions):



	Beginning Accrued Restructuring Balance 1/1/17		Pre-tax Restructuring Costs			Utilization and Foreign Exchange			Ending Accrued Restructuring Balance 12/31/2017
2017 Restructuring Actions
Severance	$	—	$	7.4		$	(3.8	)	$	3.6
Asset write-downs	—		0.5			(0.5		)	—
Facility closure and other costs	—		6.1			(4.3		)	1.8
Total 2017 Restructuring Actions	$	—	$	14.0		$	(8.6	)	$	5.4
2016 and Prior Restructuring Actions
Severance	$	10.4	$	(2.2	)	$	(6.4	)	$	1.8
Asset write-downs	—		—			—			—
Facility closure and other costs ^(a)	14.1		8.5			(8.9		)	13.7
Total 2016 and Prior Restructuring Actions	$	24.5	$	6.3		$	(15.3	)	$	15.5
Total Restructuring Actions	$	24.5	$	20.3		$	(23.9	)	$	20.9

^(a) The beginning and ending accrual for Facility closure and other costs includes a charge of approximately $12.5 million to accrue the estimated liability associated with the withdrawal from a multi-employer pension plan as a result of a restructuring action in 2016.

The actual and expected costs for our restructuring actions are as follows (in millions):



	Expected Costs		Costs incurred in 2015		Costs incurred in 2016		Costs incurred in 2017		Remaining costs at 12/31/17
2017 Restructuring Actions
Electrical Segment	$	13.0	$	—	$	—	$	10.6	$	2.4
Power Segment	3.9		—		—		3.4		0.5
Total 2017 Restructuring Actions	$	16.9	$	—	$	—	$	14.0	$	2.9
2016 Restructuring Actions
Electrical Segment	$	35.4	$	—	$	30.7	$	3.8	$	0.9
Power Segment	1.3		—		1.1		—		0.2
Total 2016 Restructuring Actions	$	36.7	$	—	$	31.8	$	3.8	$	1.1
2015 Restructuring Actions
Electrical Segment	$	23.0	$	17.3	$	3.2	$	2.5	$	—
Power Segment	1.9		1.9		—		—		—
Total 2015 and Prior Restructuring Actions	$	24.9	$	19.2	$	3.2	$	2.5	$	—
Total Restructuring Actions	$	78.5	$	19.2	$	35.0	$	20.3	$	4.0

Costs incurred in 2016 relating to 2016 Restructuring Actions in the Electrical segment in the preceding table include the $12.5 million previously mentioned charge representing the estimated withdrawal liability from a multi-employer pension plan. Any potential future liability in excess of the amount already recognized in 2016 is not included in the remaining costs at December 31, 2017 in the preceding table. Additional information about the estimated withdrawal liability is included in Note 10 — Retirement Benefits in the Notes to Consolidated Financial Statements.

Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Data

Quarterly Financial Data (Unaudited)

The table below sets forth summarized quarterly financial data for the years ended December 31, 2017 and 2016 (in millions, except per share amounts):



	Reported First Quarter		Reported Second Quarter		Reported Third Quarter		Fourth Quarter
2017
Net sales	$	852.3	$	948.3	$	950.5	$	917.7
Cost of goods sold	$	590.5	$	653.6	$	643.6	$	629.2
Gross profit	$	261.8	$	294.7	$	306.9	$	288.5
Selling & administrative expenses	$	157.7	$	164.1	$	160.5	$	165.8
Net income ⁽¹⁾	$	63.9	$	80.8	$	82.8	$	22.4
Net Income attributable to Hubbell ⁽¹⁾	$	62.8	$	79.1	$	80.8	$	20.4
Earnings per share — Basic	$	1.13	$	1.44	$	1.47	$	0.37
Earnings per share — Diluted	$	1.13	$	1.43	$	1.47	$	0.37
⁽¹⁾ Net income in the fourth quarter of 2017 includes approximately $57 million, or $1.02 per share, impact associated with the TCJA.
	Reported First Quarter		Reported Second Quarter		Reported Third Quarter		Fourth Quarter
2016
Net sales	$	834.8	$	908.8	$	907.4	$	854.2
Cost of goods sold	$	574.9	$	615.3	$	618.7	$	595.6
Gross profit	$	259.9	$	293.5	$	288.7	$	258.6
Selling & administrative expenses	$	158.0	$	161.4	$	152.7	$	150.8
Net income	$	62.0	$	82.0	$	88.1	$	65.7
Net Income attributable to Hubbell	$	60.9	$	81.0	$	86.7	$	64.4
Earnings per share — Basic	$	1.08	$	1.46	$	1.56	$	1.16
Earnings per share — Diluted	$	1.08	$	1.45	$	1.56	$	1.16

Subsequent Events

12 Months Ended

Dec. 31, 2017

Subsequent Events [Abstract]

Subsequent Events

On February 2, 2018, the Company acquired Aclara for approximately $1.1 billion. Aclara is a provider of smart infrastructure solutions for electric, gas, and water utilities, with advanced metering solutions and grid monitoring sensor technology, as well as leading software enabled installation services. The acquisition extends the Power segment's capabilities into smart automation technologies, accelerates ongoing innovation efforts to address utility customer demand for data and integrated solutions, and expands the segment's reach to a broader set of utility customers.

The Company funded the acquisition of Aclara with cash raised from a public debt offering of $450 million of long-term unsecured, unsubordinated notes, placement of $500 million under the Term Loan Agreement, and the issuance of commercial paper for the remaining purchase price.

Refer to Note 2 — Business Acquisitions and Note 11 — Debt, in the Notes to Consolidated Financial Statements for additional information.

Valuation and Qualifying Accounts and Reserves

12 Months Ended

Dec. 31, 2017

Valuation and Qualifying Accounts [Abstract]

Valuation and Qualifying Accounts and Reserves

Valuation and Qualifying Accounts and Reserves for the Years Ended December 31, 2015, 2016 and 2017

Reserves deducted in the balance sheet from the assets to which they apply (in millions):



	Balance at Beginning of Year		Additions / (Reversals) Charged to Costs and Expenses			Deductions			Acquisitions		Balance at End of Year
Allowances for doubtful accounts receivable:
Year 2015	$	3.4	$	2.7		$	(1.4	)	$	—	$	4.7
Year 2016	$	4.7	$	0.8		$	(0.8	)	$	—	$	4.7
Year 2017	$	4.7	$	1.5		$	(3.5	)	$	1.9	$	4.6
Allowance for credit memos, returns and cash discounts:
Year 2015	$	36.7	$	233.2		$	(228.4	)	$	—	$	41.5
Year 2016	$	41.5	$	249.2		$	(244.8	)	$	—	$	45.9
Year 2017	$	45.9	$	260.8		$	(256.3	)	$	0.1	$	50.5
Valuation allowance on deferred tax assets:
Year 2015	$	34.3	$	(12.3	)	$	—		$	—	$	22.0
Year 2016	$	22.0	$	0.6		$	—		$	—	$	22.6
Year 2017	$	22.6	$	(3.2	)	$	—		$	—	$	19.4

Significant Accounting Policies (Policies)	12 Months Ended
Significant Accounting Policies (Policies)	Dec. 31, 2017
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The Consolidated Financial Statements include all wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated. The Company participates in two joint ventures, one of which is accounted for using the equity method, the other has been consolidated in accordance with the consolidation accounting guidance. An analysis is performed to determine which reporting entity, if any, has a controlling financial interest in a variable interest entity (“VIE”) with a primarily qualitative analysis. The qualitative analysis is based on identifying the party that has both the power to direct the activities that most significantly impact the VIE’s economic performance (the “power criterion”) and the obligation to absorb losses from or the right to receive benefits of the VIE that could potentially be significant to the VIE (the “losses/benefit criterion”). The party that meets both these criteria is deemed to have a controlling financial interest. The party with the controlling financial interest is considered to be the primary beneficiary and as a result is required to consolidate the VIE. The Company has a 50% interest in a joint venture in Hong Kong, established as Hubbell Asia Limited (“HAL”). The principal objective of HAL is to manage the operations of its wholly-owned manufacturing company in China. Under the accounting guidance, the Company is the primary beneficiary of HAL and as a result consolidates HAL. This determination is based on the fact that HAL’s sole business purpose is to manufacture product exclusively for the Company (the power criterion) and the Company is financially responsible for ensuring HAL maintains a fixed operating margin (the losses/benefit criterion). The consolidation of HAL is not material to the Company’s consolidated financial statements.
Use of Estimates	Use of Estimates The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts in the Consolidated Financial Statements and accompanying Notes to Consolidated Financial Statements. Actual results could differ from the estimates that are used.
Revenue Recognition	Revenue Recognition The Company recognizes revenue when persuasive evidence of an arrangement exists, delivery has occurred, the price is fixed and determinable and collection is probable. Product is considered delivered to the customer once it has been shipped and title and risk of loss have been transferred. The majority of the Company’s revenue is recognized at the time of shipment. The Company recognizes less than one percent of total annual consolidated net revenue from post shipment obligations and service contracts, primarily within the Electrical segment. Revenue is recognized under these contracts when the service is completed and all conditions of sale have been met. In addition, within the Electrical segment, certain businesses sell large and complex equipment which requires construction and assembly and occasionally has long lead times. It is customary in these businesses to require a portion of the selling price to be paid in advance of construction. These payments are treated as deferred revenue and are classified in Other accrued liabilities in the Consolidated Balance Sheet. Once the equipment is shipped to the customer and meets the revenue recognition criteria, the deferred revenue is recognized in the Consolidated Statement of Income. Further, certain of our businesses provide for sales discounts and allowances based on sales volumes, specific programs and customer deductions, as is customary in the electrical products industry. These items primarily relate to sales volume incentives, special pricing allowances, and returned goods. Sales volume incentives represent rebates with specific sales volume targets for specific customers. Certain distributors qualify for price rebates by subsequently reselling the Company’s products into select channels of end users. Following a distributor’s sale of an eligible product, the distributor submits a claim for a price rebate. Customers also have a right to return goods under certain circumstances which are reasonably estimable by affected businesses. Customer returns have historically ranged from 1%-2% of gross sales. These arrangements require us to estimate at the time of sale the amounts that should not be recorded as revenue as these amounts are not expected to be collected from customers. The Company principally relies on historical experience, specific customer agreements and anticipated future trends to estimate these amounts at the time of shipment.
Shipping and Handling Fees and Costs	Shipping and Handling Fees and Costs The Company records shipping and handling costs as part of Cost of goods sold in the Consolidated Statement of Income. Any amounts billed to customers for reimbursement of shipping and handling are included in Net sales in the Consolidated Statement of Income.
Foreign Currency Translation	Foreign Currency Translation The assets and liabilities of international subsidiaries are translated to U.S. dollars at exchange rates in effect at the end of the year, and income and expense items are translated at average exchange rates in effect during the year. The effects of exchange rate fluctuations on the translated amounts of foreign currency assets and liabilities are included as translation adjustments in Accumulated other comprehensive loss within Hubbell shareholders’ equity. Gains and losses from foreign currency transactions are included in results of operations.
Cash and Cash Equivalents	Cash and Cash Equivalents The carrying value of cash equivalents approximates fair value. Cash equivalents consist of highly liquid investments with original maturities to the Company of three months or less.
Investments	Investments Investments in debt and equity securities are classified by individual security as available-for-sale, held-to-maturity or trading securities. Our available-for-sale securities, consisting of municipal bonds and the redeemable preferred stock of a privately held company, are carried on the balance sheet at fair value with current period adjustments to carrying value recorded in Accumulated other comprehensive loss within Hubbell shareholders’ equity, net of tax. Realized gains and losses are recorded in income in the period of sale. The Company’s trading securities are carried on the balance sheet at fair value and consist primarily of debt and equity mutual funds. Gains and losses associated with these trading securities are reflected in the results of operations. The Company did not have any investments classified as held-to-maturity as of December 31, 2017 and 2016.
Accounts Receivable and Allowances	Accounts Receivable and Allowances Trade accounts receivable are recorded at the invoiced amount and generally do not bear interest. The allowance for doubtful accounts is based on an estimated amount of probable credit losses in existing accounts receivable. The allowance is calculated based upon a combination of historical write-off experience, fixed percentages applied to aging categories and specific identification based upon a review of past due balances and problem accounts. Account balances are charged off against the allowance when it is determined that internal collection efforts should no longer be pursued. The Company also maintains a reserve for credit memos, cash discounts and product returns which are principally calculated based upon historical experience, specific customer agreements, as well as anticipated future trends.
Inventories	Inventories Inventories are stated at the lower of cost or market value. Approximately 71% of total net inventory value is determined utilizing the last-in, first-out (LIFO) method of inventory accounting. The cost of foreign inventories and certain domestic inventories is determined utilizing average cost or first-in, first-out (FIFO) methods of inventory accounting. Reserves for excess and obsolete inventory are provided based on current assessments about future demand compared to on-hand quantities.
Property, Plant and Equipment	Property, Plant, and Equipment Property, plant, and equipment values are stated at cost less accumulated depreciation. Maintenance and repair expenditures that do not significantly increase the life of an asset are charged to expense when incurred. Property, plant, and equipment placed in service prior to January 1, 1999 are depreciated over their estimated useful lives, principally using accelerated methods. Assets placed in service subsequent to January 1, 1999 are depreciated over their estimated useful lives, using straight-line methods. Leasehold improvements are amortized over the shorter of their economic lives or the lease term. Gains and losses arising on the disposal of property, plant and equipment are included in Operating income in the Consolidated Statement of Income.
Capitalized Computer Software Costs	Capitalized Computer Software Costs Capitalized computer software costs, net of amortization, were $15.7 million and $15.6 million at December 31, 2017 and 2016, respectively. This balance is reflected in Other long-term assets in the Consolidated Balance Sheet. Capitalized computer software is for internal use and costs primarily consist of purchased materials and services. Software is amortized on a straight-line basis over appropriate periods, generally five years. The Company recorded amortization expense of $5.6 million in 2017, $5.2 million in 2016 and $4.6 million in 2015 relating to capitalized computer software.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill represents purchase price in excess of fair values of the underlying net assets of acquired companies. Indefinite-lived intangible assets and goodwill are subject to annual impairment testing using the specific guidance and criteria described in the accounting guidance. The Company performs its goodwill impairment testing as of April 1st of each year, unless circumstances dictate the need for more frequent assessments. The accounting guidance provides entities an option of performing a qualitative assessment (a "step-zero" test) before performing a quantitative analysis. If the entity determines, on the basis of certain qualitative factors, that it is more-likely-than-not that the goodwill is not impaired, the entity would not need to proceed to the two step goodwill impairment testing process (quantitative analysis) as prescribed in the guidance. The Company applied the "step-zero" test to two of its reporting units. Based on that qualitative assessment, the Company concluded it was more-likely-than-not that the fair value of these reporting units substantially exceeded their carrying value and therefore, further quantitative analysis was not required. For each of the Company's other reporting units the Company has elected to utilize the two step goodwill impairment testing process as permitted in the accounting guidance. Step 1 compares the fair value of the Company’s reporting units to their carrying values. If the fair value of the reporting unit exceeds its carrying value, no further analysis is necessary. If the carrying value of the reporting unit exceeds its fair value, Step 2 must be completed to determine the amount of impairment. Goodwill impairment testing requires judgment, including the identification of reporting units, assigning assets and liabilities to reporting units and determining the fair value of each reporting unit. Significant judgments required to estimate the fair value of reporting units include estimating future cash flows, determining appropriate discount rates and other assumptions. The Company uses internal discounted cash flow estimates to determine fair value. These cash flow estimates are derived from historical experience and future long-term business plans and the application of an appropriate discount rate. Changes in these estimates and assumptions could materially affect the determination of fair value and/or goodwill impairment for each reporting unit. The Company’s estimated aggregate fair value of its reporting units are reasonable when compared to the Company’s market capitalization on the valuation date. As of April 1, 2017, our impairment testing resulted in implied fair values for each reporting unit that exceeded the reporting unit’s carrying value, including goodwill. The Company did not have any reporting units at risk of failing Step 1 of the impairment test as the excess of the implied fair value significantly exceeded the carrying value of the reporting units. Additionally, the Company did not have any reporting units with zero or negative carrying amounts. The Company has not recorded any goodwill impairments since the initial adoption of the accounting guidance in 2002. The Company’s intangible assets consist primarily of customer relationships, tradenames and patents. Intangible assets with definite lives are amortized over periods generally ranging from 5-30 years. The Company amortizes intangible assets with definite lives using either an accelerated method that reflects the pattern in which economic benefits of the intangible assets are consumed and results in higher amortization in the earlier years of the assets useful life, or using a straight line method. Approximately 60% of the gross value of definite-lived intangible assets follow an accelerated amortization method. These definite lived intangibles are tested for impairment whenever events or circumstances indicate that the carrying amount of an asset (asset group) may not be recoverable. An impairment loss is recognized when the carrying amount of an asset exceeds the estimated undiscounted cash flows used in determining the fair value of the asset. The Company did not record any material impairments related to its definite lived intangible assets in 2017, 2016 or 2015. The Company also has some tradenames that are considered to be indefinite-lived intangible assets. These indefinite-lived intangible assets are not amortized and are tested for impairment annually, unless circumstances dictate the need for more frequent assessment. The accounting guidance related to testing indefinite-lived intangible assets for impairment provides entities an option of performing a qualitative assessment before calculating the fair value of the asset. If the entity determines, on the basis of certain qualitative factors, that it is more-likely-than-not that the asset is not impaired, the entity would not need to calculate the fair value of the asset. The Company performed the qualitative assessment which resulted in no impairment in 2017, 2016 and 2015.
Other Long-Lived Assets	Other Long-Lived Assets The Company reviews depreciable long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount may not be fully recoverable. If such a change in circumstances occurs, the related estimated future undiscounted cash flows expected to result from the use of the asset group and its eventual disposition is compared to the carrying amount. If the sum of the expected cash flows is less than the carrying amount, an impairment charge is recorded. The impairment charge is measured as the amount by which the carrying amount exceeds the fair value of the asset. The fair value of impaired assets is determined using expected cash flow estimates, quoted market prices when available and appraisals as appropriate. The Company did not record any material impairment charges in 2017, 2016 or 2015.
Accrued Insurance	Accrued Insurance The Company retains a significant portion of the risks associated with workers’ compensation, medical, automobile and general liability insurance. The Company estimates self-insurance liabilities using a number of factors, including historical claims experience, demographic factors, and other actuarial assumptions. The accrued liabilities associated with these programs are based on the Company’s estimate of the ultimate costs to settle known claims as well as claims incurred but not reported as of the balance sheet date. The Company periodically reviews the assumptions with a third party actuary to determine the adequacy of these self-insurance reserves.
Income Taxes	Income Taxes The Company operates within multiple taxing jurisdictions and is subject to audit in these jurisdictions. The IRS and other tax authorities routinely examine the Company’s tax returns. These audits can involve complex issues which may require an extended period of time to resolve. The Company makes adequate provisions for best estimates of exposures on previously filed tax returns. Deferred income taxes are recognized for the tax consequence of differences between financial statement carrying amounts and the tax basis of assets and liabilities by applying the currently enacted statutory tax rates in accordance with the accounting guidance for income taxes. The effect of a change in statutory tax rates is recognized in the period that includes the enactment date. Additionally, deferred tax assets are required to be reduced by a valuation allowance if it is more-likely-than-not that some portion or all of the deferred tax asset will not be realized. The Company uses factors to assess the likelihood of realization of deferred tax assets such as the forecast of future taxable income and available tax planning strategies that could be implemented to realize the deferred tax assets. In addition, the accounting guidance prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of the tax position taken or expected to be taken in a tax return. For any amount of benefit to be recognized, it must be determined that it is more-likely-than-not that a tax position will be sustained upon examination by taxing authorities based on the technical merits of the position. The amount of benefit to be recognized is based on the Company’s assertion of the most likely outcome resulting from an examination, including resolution of any related appeals or litigation processes. Companies are required to reflect only those tax positions that are more-likely-than-not to be sustained. We have accounted for the estimated impact of the TCJA based on the guidance outlined in SAB 118. The accounting for the income tax effects of the TCJA may include provisional amounts during the one-year measurement period from the date of enactment. Accordingly, the Company has included in the current period financial statements a provisional amount with respect to the deemed repatriation provisions of the TCJA, the revaluation of U.S. deferred taxes and the U.S. and foreign tax costs associated with anticipated remittances related to certain of our outside basis differences. We have also included provisional amounts with respect to those states with current conformity to the Internal Revenue Code all of which will be subject to change during the measurement period. The TCJA also contains a new tax law that may subject the Company to a tax on Global Intangible Low-Taxed Income (GILTI), beginning in 2018. GILTI is a tax on foreign income in excess of a deemed return on tangible assets of foreign corporations. The FASB has provided that Companies subject to GILTI have the option to account for the GILTI tax as a period cost if and when incurred, or to recognize deferred taxes for temporary differences, including outside basis differences, expected to reverse as GILTI. We have elected to account for GILTI as a period cost. See Note 12 — Income Taxes for additional information.
Research and Development	Research and Development Research and development expenditures represent costs to discover and/or apply new knowledge in developing a new product, process, or in bringing about a significant improvement to an existing product or process. Research and development expenses are recorded as a component of Cost of goods sold. Expenses for research and development were approximately 3% of Cost of goods sold in 2017 and 2% in 2016 and 2015.
Retirement Benefits	Retirement Benefits The Company maintains various defined benefit pension plans for some of its U.S. and foreign employees. The accounting guidance for retirement benefits requires the Company to recognize the funded status of its defined benefit pension and postretirement plans as an asset or liability in the Consolidated Balance Sheet. Gains or losses, prior service costs or credits, and transition assets or obligations that have not yet been included in net periodic benefit cost as of the end of the year are recognized as components of Accumulated other comprehensive loss, net of tax, within Hubbell shareholders’ equity. The Company’s policy is to fund pension costs within the ranges prescribed by applicable regulations. In addition to providing defined benefit pension benefits, the Company provides health care and life insurance benefits for some of its active and retired employees. The Company’s policy is to fund these benefits through insurance premiums or as actual expenditures are made. See also Note 10 — Retirement Benefits.
Earnings Per Share	Earnings Per Share Restricted stock granted by the Company is considered a participating security since it contains a non-forfeitable right to dividends. As a result, the earnings per share accounting guidance requires the Company to use the two-class method for calculating earnings per share. The two-class method is an earnings allocation formula that determines earnings per share for common stock and participating securities. Basic earnings per share is calculated as net income available to common shareholders divided by the weighted average number of shares of common stock outstanding. Earnings per diluted share is calculated as net income available to common shareholders divided by the weighted average number of shares outstanding of common stock plus the incremental shares outstanding assuming the exercise of dilutive stock options, stock appreciation rights and performance shares. See also Note 17 — Earnings Per Share.
Stock-Based Compensation	Stock-Based Compensation The Company recognizes the grant-date fair value of all stock-based awards on a straight-line basis over their respective requisite service periods (generally equal to an award’s vesting period). A stock-based award is considered vested for expense attribution purposes when the retention of the award is no longer contingent on providing subsequent service. Accordingly, the Company recognizes compensation cost immediately for awards granted to retirement-eligible individuals or over the period from the grant date to the date retirement eligibility is achieved, if less than the stated vesting period. The expense is recorded in Cost of goods sold and S&A expense in the Consolidated Statement of Income based on the recipients’ respective functions within the organization. The Company records deferred tax assets for awards that will result in deductions on its tax returns, based upon the amount of compensation cost recognized and the statutory tax rate in the jurisdiction in which it will receive a deduction. The Company adopted ASU 2016-09 relating to the accounting for share-based payments on January 1, 2017. The standard requires that differences between the deferred tax assets recognized for financial reporting purposes and the actual tax deduction reported on the Company's tax return be recoded as a component of income tax expense. Prior to the adoption of the standard, differences between the deferred tax assets recognized for financial reporting purposes and the actual tax deduction reported in the Company’s tax return were recognized in Additional paid-in capital to the extent that previously recognized credits to paid-in capital were still available. See also Note 16 — Stock-Based Compensation.
Derivatives	Derivatives In order to limit financial risk in the management of its assets, liabilities and debt, the Company may use derivative financial instruments such as foreign currency hedges, interest rate hedges and interest rate swaps. All derivative financial instruments are matched with an existing Company asset, liability or proposed transaction. The Company does not speculate or use leverage when trading a derivative product. Market value gains or losses on the derivative financial instrument are recognized in income when the effects of the related price changes of the underlying asset or liability are recognized in income. See Note 13 — Financial Instruments and Fair Value Measurement for more information regarding our derivative instruments.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In response to the TCJA, which was signed into law on December 22, 2017, the Securities and Exchange Commission’s Office of the Chief Accountant published SAB 118. SAB 118 addresses the requirements to account for the impact of a change in tax law or tax rates in the period of enactment. Specifically, SAB 118 provides guidance for issuers that are not able to complete the accounting for the income tax effects of the TCJA by the time financial statements are issued for the reporting period that includes the enactment date (“enactment period financials”). Pursuant to SAB 118, if the accounting for specific income tax effects of the TCJA is incomplete at the time the financial statements are issued, a company should provide a provisional amount for specific income tax effects for which a reasonable estimate can be determined. For any specific income tax effects of the TCJA for which a reasonable estimate cannot be determined because additional information, data, analysis or preparation is required, a company should not report a provisional amount but continue to apply the rules in effect immediately prior to enactment. For income tax effects for which a company was not able to determine a reasonable estimate in the enactment period financials, a provisional amount must be recorded in the first reporting period in which a reasonable estimate can be determined. Under SAB 118, the measurement period for accounting for the 2017 Act begins in the period of enactment and ends when an entity has obtained, prepared and analyzed the information necessary to complete the accounting requirements under ASC 740 (the “measurement period”), but in no event can the measurement period extend beyond one year from the TCJA’s enactment date. Any provisional amount or adjustment to a provisional amount included in a company’s financial statements during the measurement period should be included in income from continuing operations as an adjustment to tax expense or benefit in the reporting period the amounts are determined. In March 2017, the Financial Accounting Standards Board ("FASB") issued an Accounting Standards Update (ASU 2017-07) on the presentation of net periodic pension cost and net periodic post-retirement benefit cost. The new guidance requires the service cost component of net periodic pension and post-retirement benefit costs to be reported in the same income statement line item as other employee compensation costs, and the other non-service components to be reported outside of operating income. This new guidance is effective for fiscal years beginning after December 15, 2017 and must be applied on a retrospective basis. Upon adoption, the Company expects 2016 Operating income to increase by $12.0 million and 2017 Operating income to increase by $15.0 million, due to the removal of the non-service components of net periodic pension and post-retirement benefit costs. The Company expects a corresponding increase to Other expense, net, resulting in zero impact to net income in both periods. In August 2016, the FASB issued an Accounting Standards Update (ASU 2016-15) to provide additional guidance and reduce diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows. The Company adopted the standard during the third quarter of 2017, and the comparable periods within the Consolidated Statements of Cash Flows have been recast to reflect adoption. The adoption did not have a material impact on the Company's financial statements. In March 2016, the FASB issued an Accounting Standards Update (ASU 2016-09) relating to the accounting for share-based payments. The new guidance requires all income tax effects of share-based awards to be recognized in the income statement when the awards vest or are settled, and allows companies an additional election in the method to estimate forfeitures of share-based payments. The new guidance also requires excess tax benefits to be classified as an operating activity in the statement of cash flows, and cash paid to a tax authority when shares are withheld to satisfy the employer's statutory income tax withholdings be classified as a financing activity. The Company adopted the standard on January 1, 2017. The Company elected to adopt all provisions impacting the Consolidated Statements of Cash Flows retrospectively; as such, the comparable periods within the Consolidated Statements of Cash Flows have been recast to reflect the adoption. The income statement provisions of the new guidance have been adopted prospectively. There is no change to the Company's accounting policy with respect to estimation of forfeitures. The adoption did not have a material impact on the Company's financial statements. In February 2016, the FASB issued an Accounting Standards Update (ASU 2016-02) related to the accounting and financial statement presentation for leases. This new guidance will require a lessee to recognize a right-to-use asset and a lease liability for both financing and operating leases, with a policy election permitting an exception to this guidance for leases with a term of twelve months or less. For financing leases, the lessee will recognize interest expense and amortization of the right-of-use asset, and for operating leases, the lessee will recognize a straight-line lease expense. This guidance is effective for fiscal years beginning after December 15, 2018, with early adoption permitted. The new standard must be adopted using a modified retrospective transition at the beginning of the earliest comparative period presented. The Company expects to recognize approximately $100 million of right-of-use assets and corresponding lease liabilities on the balance sheet upon adoption. The Company does not expect the adoption will have a material impact on results of operations. In May 2014, the FASB issued an Accounting Standards Update (ASU 2014-09) related to new revenue recognition guidance that supersedes the existing revenue recognition guidance and most industry-specific guidance applicable to revenue recognition. According to the new guidance, an entity will apply a principles-based five step model to recognize revenue upon the transfer of promised goods or services to customers and in an amount that reflects the consideration for which the entity expects to be entitled in exchange for those goods or services. Subsequently, the FASB has issued amendments to certain aspects of the guidance including the effective date. The Company will adopt the guidance in the first quarter of 2018 using the modified-retrospective method. Based on the reviews and assessments performed to date, the Company expects the pattern of revenue recognition for substantially all of its businesses to be unchanged, and that upon adoption revenue will generally continue to be recognized at a single point in time when control is transferred to the customer. The Company anticipates an immaterial impact to retained earnings upon adoption, as well as an immaterial balance sheet impact related to the classification of amounts associated with sales returns reserves.

Inventory (Tables)

12 Months Ended

Dec. 31, 2017

Inventory Disclosure [Abstract]

Schedule of Inventory

Inventories are classified as follows at December 31, (in millions):



	2017			2016
Raw material	$	190.0		$	162.7
Work-in-process	115.8			102.8
Finished goods	390.5			327.9
	696.3			593.4
Excess of FIFO over LIFO cost basis	(61.6		)	(61.0		)
INVENTORIES, NET	$	634.7		$	532.4

Goodwill and Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

Changes in the carrying amounts of goodwill for the years ended December 31, 2017 and 2016, by segment, were as follows (in millions):



	Segment
	Electrical			Power		Total
BALANCE AT DECEMBER 31, 2015	$	611.2		$	317.3	$	928.5
Current year acquisitions	49.4			20.6		70.0
Foreign currency translation and prior year acquisitions	(8.6		)	1.1		(7.5		)
BALANCE AT DECEMBER 31, 2016	$	652.0		$	339.0	$	991.0
Current year acquisitions	58.7			29.8		88.5
Foreign currency translation and prior year acquisitions	6.9			2.6		9.5
BALANCE AT DECEMBER 31, 2017	$	717.6		$	371.4	$	1,089.0

Schedule of Identifiable Intangible Assets

Identifiable intangible assets are recorded in Intangible assets, net in the Consolidated Balance Sheet. Identifiable intangible assets are comprised of the following (in millions):



	December 31, 2017					December 31, 2016
	Gross Amount		Accumulated Amortization			Gross Amount		Accumulated Amortization
Definite-lived:
Patents, tradenames and trademarks	$	151.4	$	(50.1	)	$	143.7	$	(43.4	)
Customer/agent relationships and other	462.0		(156.7		)	405.9		(128.0		)
TOTAL DEFINITE-LIVED INTANGIBLES	613.4		(206.8		)	549.6		(171.4		)
Indefinite-lived:
Tradenames and other	53.8		—			53.3		—
TOTAL INTANGIBLE ASSETS	$	667.2	$	(206.8	)	$	602.9	$	(171.4	)

Investment (Table)

12 Months Ended

Dec. 31, 2017

Investments [Abstract]

Schedule of Investments, Amortized Cost Basis

The following table sets forth selected data with respect to the Company’s investments at December 31, (in millions):



	2017											2016
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Carrying Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Carrying Value
Available-for-sale securities	$	59.3	$	0.1	$	(1.0	)	$	58.4	$	58.4	$	58.6	$	0.3	$	(1.5	)	$	57.4	$	57.4
Trading securities	8.9		4.9		—			13.8		13.8		7.1		3.1		—			10.2		10.2
TOTAL INVESTMENTS	$	68.2	$	5.0	$	(1.0	)	$	72.2	$	72.2	$	65.7	$	3.4	$	(1.5	)	$	67.6	$	67.6

Schedule of Contractual Maturities of Available-For-Sale Investments

Contractual maturities of our investments in available-for-sale securities at December 31, 2017 were as follows (in millions):



	Amortized Cost		Fair Value
Available-for-sale securities
Due within 1 year	$	14.5	$	14.5
After 1 year but within 5 years	31.5		30.7
After 5 years but within 10 years	10.9		10.8
Due after 10 years	2.4		2.4
TOTAL	$	59.3	$	58.4

Property, Plant and Equipment (Table)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Schedule of Property, Plant, and Equipment

Property, plant, and equipment, carried at cost, is summarized as follows at December 31, (in millions):



	2017			2016
Land	$	40.0		$	43.1
Buildings and improvements	272.2			268.7
Machinery, tools, and equipment	806.2			784.7
Construction-in-progress	43.4			36.9
Gross property, plant, and equipment	1,161.8			1,133.4
Less accumulated depreciation	(703.5		)	(693.6		)
NET PROPERTY, PLANT, AND EQUIPMENT	$	458.3		$	439.8

Retirement Benefits (Tables)

12 Months Ended

Dec. 31, 2017

Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]

Schedule of Changes in Benefit Obligation and the Plan Assets



	Pension Benefits						Other Benefits
	2017			2016			2017			2016
Change in benefit obligation
Benefit obligation at beginning of year	$	917.4		$	912.3		$	26.2		$	26.6
Service cost	5.9			12.9			0.1			—
Interest cost	37.2			41.9			1.0			1.2
Plan participants’ contributions	0.6			0.5			—			—
Amendments	0.3			(34.1		)	—			—
Actuarial loss	29.7			88.0			1.4			0.2
Currency impact	9.7			(18.5		)	—			—
Other	(0.4		)	(0.5		)	—			—
Benefits paid	(44.3		)	(85.1		)	(1.7		)	(1.8		)
Benefit obligation at end of year	$	956.1		$	917.4		$	27.0		$	26.2
Change in plan assets
Fair value of plan assets at beginning of year	$	705.1		$	757.6		$	—		$	—
Actual return on plan assets	58.6			23.6			—			—
Employer contributions	9.8			24.3			1.7			1.8
Plan participants’ contributions	0.6			0.5			—			—
Currency impact	9.0			(15.8		)	—			—
Benefits paid	(44.3		)	(85.1		)	(1.7		)	(1.8		)
Fair value of plan assets at end of year	$	738.8		$	705.1		$	—		$	—
FUNDED STATUS	$	(217.3	)	$	(212.3	)	$	(27.0	)	$	(26.2	)
Amounts recognized in the consolidated balance sheet consist of:
Prepaid pensions (included in Other long-term assets)	$	1.5		$	1.7		$	—		$	—
Accrued benefit liability (short-term and long-term)	(218.8		)	(214.0		)	(27.0		)	(26.2		)
NET AMOUNT RECOGNIZED IN THE CONSOLIDATED BALANCE SHEET	$	(217.3	)	$	(212.3	)	$	(27.0	)	$	(26.2	)
Amounts recognized in Accumulated other comprehensive loss (income) consist of:
Net actuarial loss	$	270.1		$	274.2		$	3.0		$	1.7
Prior service cost (credit)	0.6			0.4			(2.3		)	(3.3		)
NET AMOUNT RECOGNIZED IN ACCUMULATED OTHER COMPREHENSIVE LOSS	$	270.7		$	274.6		$	0.7		$	(1.6	)

Summary of Accumulated Benefit Obligations in Excess of Plan Assets

Information with respect to plans with accumulated benefit obligations in excess of plan assets is as follows, (in millions):



	2017		2016
Projected benefit obligation	$	842.7	$	801.1
Accumulated benefit obligation	$	826.5	$	781.4
Fair value of plan assets	$	626.3	$	603.1

Schedule of the Components of Pension and Other Benefit Costs

The following table sets forth the components of pension and other benefit costs for the years ended December 31, (in millions):



	Pension Benefits									Other Benefits
	2017			2016			2015			2017			2016			2015
Components of net periodic benefit cost:
Service cost	$	5.9		$	12.9		$	17.7		$	0.1		$	—		$	0.1
Interest cost	37.2			41.9			40.5			1.0			1.2			1.0
Expected return on plan assets	(34.1		)	(44.3		)	(53.2		)	—			—			—
Amortization of prior service cost (credit)	0.1			0.1			0.2			(1.0		)	(1.0		)	(1.0		)
Amortization of actuarial losses (gains)	11.4			13.9			12.1			—			—			(0.1		)
Curtailment and settlement losses	0.4			0.2			—			—			—			—
Net periodic benefit cost	$	20.9		$	24.7		$	17.3		$	0.1		$	0.2		$	—
Changes recognized in other comprehensive loss (income), before tax:
Current year net actuarial loss	$	4.2		$	72.0		$	37.0		$	1.4		$	0.2		$	0.5
Current year prior service credit	0.3			—			—			—			—			—
Amortization of prior service (cost) credit	(0.1		)	(0.1		)	(0.2		)	1.0			1.0			1.0
Amortization of net actuarial (losses) gains	(11.4		)	(13.9		)	(12.1		)	—			—			0.1
Currency impact	3.5			(4.0		)	(0.1		)	—			—			—
Other adjustments	(0.4		)	(0.2		)	—			—			—			—
Total recognized in other comprehensive loss	(3.9		)	53.8			24.6			2.4			1.2			1.6
TOTAL RECOGNIZED IN NET PERIODIC PENSION COST AND OTHER COMPREHENSIVE LOSS	$	17.0		$	78.5		$	41.9		$	2.5		$	1.4		$	1.6
Amortization expected to be recognized through income during 2018
Amortization of prior service cost (credit)	$	0.1								$	(1.0	)
Amortization of net loss	10.9									0.2
TOTAL EXPECTED TO BE RECOGNIZED THROUGH INCOME DURING NEXT FISCAL YEAR	$	11.0								$	(0.8	)

Schedule of Assumptions Used to Determine the Projected Benefit Obligation

The following assumptions were used to determine the projected benefit obligations at the measurement date and the net periodic benefit cost for the year:



	Pension Benefits						Other Benefits
	2017		2016		2015		2017		2016		2015
Weighted-average assumptions used to determine benefit obligations at December 31,
Discount rate	3.67	%	4.12	%	4.71	%	3.70	%	4.10	%	4.60	%
Rate of compensation increase	3.24	%	3.55	%	3.59	%	4.00	%	3.93	%	3.92	%
Weighted-average assumptions used to determine net periodic benefit cost for years ended December 31,
Discount rate	4.12	%	4.71	%	4.23	%	4.10	%	4.60	%	4.10	%
Expected return on plan assets	4.94	%	6.04	%	6.36	%	N/A		N/A		N/A
Rate of compensation increase	3.55	%	3.59	%	3.15	%	3.93	%	3.92	%	3.60	%

Schedule of Health Care Cost Trend Rates

The assumed health care cost trend rates used to determine the projected postretirement benefit obligation are as follows:



	Other Benefits
	2017		2016		2015
Assumed health care cost trend rates at December 31,
Health care cost trend assumed for next year	7.0	%	7.2	%	7.4	%
Rate to which the cost trend is assumed to decline	5.0	%	5.0	%	5.0	%
Year that the rate reaches the ultimate trend rate	2028		2028		2028

Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates

A one-percentage-point change in assumed health care cost trend rates would have the following effects (in millions):



	One Percentage Point Increase		One Percentage Point Decrease
Effect on total of service and interest cost	$	0.1	$	(0.1	)
Effect on postretirement benefit obligation	$	1.8	$	(1.5	)

Schedule of Allocation of Plan Assets



	Percentage of Plan Assets
	Target		Actual
Asset Category	2018		2017		2016
Equity securities	19	%	18	%	16	%
Debt securities & Cash	64	%	65	%	65	%
Alternative Investments	17	%	17	%	19	%
TOTAL	100	%	100	%	100	%

Schedule of Changes in Fair Value of Plan Assets

The fair value of the Company’s pension plan assets at December 31, 2017 and 2016, by asset category are as follows (in millions):



				Quoted Prices in Active Markets for Identical Assets		Quoted Prices in Active Market for Similar Asset			Significant Unobservable Inputs		Investments Priced Using Net Asset Value
Asset Category	Total			(Level 1)		(Level 2)			(Level 3)
Cash and cash equivalents	$	47.9		$	47.9	$	—		$	—	$	—
Equity securities:
US Large-cap ^(a)	15.6			15.6		—			—		—
US Mid-cap and Small-cap Growth ^(b)	3.1			3.1		—			—		—
International Large-cap	30.9			30.9		—			—		—
Emerging Markets ^(c)	8.6			8.6		—			—		—
Fixed Income Securities:
US Treasuries	402.2			—		402.2			—		—
Corporate Bonds^(d)	10.6			0.3		10.3			—		—
Asset Backed Securities and Other	75.6			—		75.6			—		—
Derivatives:
Assets ^(e)	4.6			1.5		3.1			—		—
(Liabilities) ^(e)	(1.3		)	0.1		(1.4		)	—		—
Alternative Investment Funds ^(f)	123.0			50.6		—			—		72.4
Common Pooled Fund ^(g)	18.0			0.8		17.2			—		—
BALANCE AT DECEMBER 31, 2017	$	738.8		$	159.4	$	507.0		$	—	$	72.4



				Quoted Prices in Active Markets for Identical Assets			Quoted Prices in Active Market for Similar Asset			Significant Unobservable Inputs		Investments Priced Using Net Asset Value
Asset Category	Total			(Level 1)			(Level 2)			(Level 3)
Cash and cash equivalents	$	48.3		$	48.3		$	—		$	—	$	—
Equity securities:
US Large-cap ^(a)	29.5			29.5			—			—		—
US Mid-cap and Small-cap Growth^(b)	42.6			42.6			—			—		—
International Large-cap	27.6			27.6			—			—		—
Emerging Markets ^(c)	5.9			5.9			—			—		—
Fixed Income Securities:
US Treasuries	334.5			—			334.5			—		—
Corporate Bonds ^(d)	21.0			0.3			20.6			0.1		—
Asset Backed Securities and Other	45.0			—			45.0			—		—
Derivatives:
Assets ^(e)	2.1			0.5			1.6			—		—
(Liabilities) ^(e)	(1.1		)	(0.5		)	(0.6		)	—		—
Alternative Investment Funds ^(f)	133.5			47.0			—			—		86.5
Common Pooled Funds ^(g)	16.2			0.8			15.4			—		—
BALANCE AT DECEMBER 31, 2016	$	705.1		$	202.0		$	416.5		$	0.1	$	86.5


(a)	Includes an actively managed portfolio of large-cap US stocks.


(b)	Includes $40.0 million of the Company’s common stock at December 31, 2016, and an investment in a small cap open ended mutual fund.


(c)	Includes open ended emerging markets mutual funds.


(d)	Includes primarily investment grade bonds from diverse industries.


(e)	Includes primarily U.S. and foreign equity futures as well as foreign fixed income futures and positions in U.S. Treasury futures to adjust the duration of the portfolio.


(f)	Includes investments in hedge funds, including fund of funds products and open end mutual funds.


(g)	Investments in Common Pooled Funds, consisting of equities and fixed income securities.

Schedule of Expected Benefit Payments

The following domestic and foreign benefit payments, which reflect future service, as appropriate, are expected to be paid as follows, (in millions):



	Pension Benefits		Other Benefits
2018	$	42.9	$	2.4
2019	$	44.4	$	2.3
2020	$	46.1	$	2.2
2021	$	47.6	$	2.2
2022	$	49.8	$	2.0
2023-2027	$	267.2	$	8.8

Debt (Tables)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Schedule of Debt

Other information related to short-term debt at December 31, is summarized below:



	2017		2016
Interest rate on short-term debt:
At year end^(a)	1.95	%	6.89	%
Paid during the year (weighted average)	2.24	%	0.72	%


(a)	The interest rate at December 31, 2016 reflects short term borrowings which are predominately related to our operations in China and Brazil and reflect market interest rates in those regions.

The following table sets forth the Company’s long-term debt at December 31, (in millions):



	Maturity	2017		2016
Senior notes at 5.95%, net of unamortized discount and unamortized debt issuance costs	2018	$	—	$	299.3
Senior notes at 3.625%, net of unamortized discount and unamortized debt issuance costs	2022	297.9		297.5
Senior notes at 3.35%, net of unamortized discount and unamortized debt issuance costs	2026	394.4		393.7
Senior notes at 3.15%, net of unamortized discount and unamortized debt issuance costs	2027	294.8		—
TOTAL LONG-TERM DEBT		$	987.1	$	990.5

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Schedule of Selected Data with Respect to the Company's Income Tax Provision

The following table sets forth selected data with respect to the Company’s income tax provisions for the years ended December 31, (in millions):



	2017			2016			2015
Income before income taxes:
United States	$	354.7		$	349.5		$	347.2
International	88.4			80.9			71.4
TOTAL INCOME BEFORE INCOME TAXES	$	443.1		$	430.4		$	418.6
Provision for income taxes — current:
Federal	$	164.1		$	85.5		$	110.4
State	15.3			17.4			13.7
International	28.1			17.0			17.6
Total provision — current	207.5			119.9			141.7
Provision for income taxes — deferred:
Federal	(10.4		)	13.5			(1.7		)
State	(0.9		)	1.3			0.4
International	(3.0		)	(2.1		)	(3.9		)
Total provision — deferred	(14.3		)	12.7			(5.2		)
TOTAL PROVISION FOR INCOME TAXES	$	193.2		$	132.6		$	136.5

Schedule of Deferred Tax Assets and Liabilities



	2017			2016
Deferred tax assets:
Inventories	$	5.2		$	8.8
Income tax credits	21.0			30.9
Accrued liabilities	17.2			20.8
Pension	55.8			77.6
Post retirement and post employment benefits	6.5			10.0
Stock-based compensation	13.4			17.5
Net operating loss carryforwards	19.0			27.2
Miscellaneous other	10.7			7.5
Gross deferred tax assets	148.8			200.3
Valuation allowance	(19.4		)	(22.6		)
Total deferred tax assets, net of valuation allowance	129.4			177.7
Deferred tax liabilities:
Acquisition basis difference	(116.5		)	(162.1		)
Property, plant, and equipment	(30.3		)	(46.3		)
Total deferred tax liabilities	(146.8		)	(208.4		)
TOTAL NET DEFERRED TAX LIABILITY	$	(17.4	)	$	(30.7	)
Deferred taxes are reflected in the Consolidated Balance Sheet as follows:
Non-current tax assets (included in Other long-term assets)	6.3			10.5
Non-current tax liabilities (included in Other Non-Current Liabilities)	(23.7		)	(41.2		)
TOTAL NET DEFERRED TAX LIABILITY	$	(17.4	)	$	(30.7	)

Reconciliation of Beginning and Ending Unrecognized Tax Benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in millions):



	2017			2016			2015
Unrecognized tax benefits at beginning of year	$	20.2		$	20.3		$	21.6
Additions based on tax positions relating to the current year	13.6			2.8			2.9
Reductions based on expiration of statute of limitations	(1.4		)	(5.7		)	(2.8		)
Additions to tax positions relating to previous years	1.0			2.9			0.4
Settlements	(3.9		)	(0.1		)	(1.8		)
TOTAL UNRECOGNIZED TAX BENEFITS	$	29.5		$	20.2		$	20.3

Schedule of Effective Income Tax Rate Reconciliation

The consolidated effective income tax rate varied from the United States federal statutory income tax rate for the years ended December 31, as follows:



	2017		2016		2015
Federal statutory income tax rate	35.0	%	35.0	%	35.0	%
State income taxes, net of federal benefit	1.2		2.4		2.3
Foreign income taxes	(3.1	)	(3.4	)	(3.9	)
TCJA and related	12.8		—		—
Other, net	(2.3	)	(3.2	)	(0.8	)
CONSOLIDATED EFFECTIVE INCOME TAX RATE	43.6	%	30.8	%	32.6	%

Financial Instruments and Fair Value Measurement (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Schedule of Financial Assets and Liabilities Accounted for at Fair Value



Asset (Liability)	Quoted Prices in Active Markets for Identical Assets (Level 1)			Quoted Prices in Active Markets for Similar Assets (Level 2)			Unobservable inputs for which little or no market data exists (Level 3)		Total
Money market funds^(a)	$	126.9		$	—		$	—	$	126.9
Available for sale investments	—			54.3			4.1		58.4
Trading securities	13.8			—			—		13.8
Deferred compensation plan liabilities	(13.8		)	—			—		(13.8		)
Derivatives:
Forward exchange contracts-Assets^(b)	—			0.2			—		0.2
Forward exchange contracts-(Liabilities)^(c)	—			(0.7		)	—		(0.7		)
BALANCE AT DECEMBER 31, 2017	$	126.9		$	53.8		$	4.1	$	184.8



Asset (Liability)	Quoted Prices in Active Markets for Identical Assets (Level 1)			Quoted Prices in Active Markets for Similar Assets (Level 2)			Unobservable inputs for which little or no market data exists (Level 3)		Total
Money market funds ^(a)	$	263.5		$	—		$	—	$	263.5
Available-for-sale investments	—			53.6			3.8		57.4
Trading securities	10.2			—			—		10.2
Deferred compensation plan liabilities	(10.2		)	—			—		(10.2		)
Derivatives:
Forward exchange contracts-Assets^(b)	—			0.8			—		0.8
Forward exchange contracts-(Liabilities)^(c)	—			(0.1		)	—		(0.1		)
BALANCE AT DECEMBER 31, 2016	$	263.5		$	54.3		$	3.8	$	321.6


(a)	Money market funds are included in Cash and cash equivalents in the Consolidated Balance Sheet.


(b)	Forward exchange contracts-Assets are reflected in Other current assets in the Consolidated Balance Sheet.


(c)	Forward exchange contracts-(Liabilities) are reflected in Other accrued liabilities in the Consolidated Balance Sheet.

Schedule of Derivative Instruments and Cash Flow Hedging Relationships

The following table summarizes the results of cash flow hedging relationships for years ended December 31, (in millions):



	Derivative Gain/(Loss) Recognized in Accumulated Other Comprehensive Loss, net of tax						Location of Gain/(Loss) when reclassified	Gain/(Loss) Reclassified into Earnings (Effective Portion), net of tax
Derivative Instrument	2017			2016			(Effective Portion)	2017			2016
Forward exchange contract	$	(1.7	)	$	(1.4	)	Net sales	$	(0.3	)	$	(0.3	)
							Cost of goods sold	$	(0.6	)	$	0.3

Capital Stock (Tables)

12 Months Ended

Dec. 31, 2017

Stockholders' Equity Note [Abstract]

Schedule of Activity in the Company's Common Shares Outstanding

Activity in the Company’s common shares outstanding is set forth below for the three years ended December 31, 2017 (in thousands):



	Common Stock
	Class A		Class B		Common Stock
OUTSTANDING AT DECEMBER 31, 2014	7,167		51,329		—
Exercise of stock options/stock appreciation rights	—		29		—
Director compensation arrangements, net	—		17		—
Restricted/performance shares activity, net of forfeitures	—		122		—
Acquisition/surrender of shares	—		(708	)	(119	)
Share reclassification	(7,167	)	(50,789	)	57,956
OUTSTANDING AT DECEMBER 31, 2015	—		—		57,837
Exercise of stock appreciation rights	—		—		78
Director compensation arrangements, net	—		—		6
Restricted/performance shares activity, net of forfeitures	—		—		98
Acquisition/surrender of shares	—		—		(2,487	)
OUTSTANDING AT DECEMBER 31, 2016	—		—		55,532
Exercise of stock appreciation rights	—		—		53
Director compensation arrangements, net	—		—		10
Restricted/performance shares activity, net of forfeitures	—		—		89
Acquisition/surrender of shares	—		—		(802	)
OUTSTANDING AT DECEMBER 31, 2017	—		—		54,882

Schedule of Shares of the Company's Reserved Common Stock

Shares of the Company’s common stock were reserved at December 31, 2017 as follows (in thousands):



	Common Stock
	Common Stock
Future grant of stock-based compensation	2,609
Shares reserved under other equity compensation plans	161
TOTAL	2,770

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section S99
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=65877616&loc=d3e177068-122764

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(d))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
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-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21553-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=65888546&loc=d3e21300-112643

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(27))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21538-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21488-112644

+ Details

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

The following table summarizes the assumptions used in estimating the fair value of these awards:



Grant Date	Stock Price on Measurement Date		Expected Volatility		Risk Free Interest Rate		Expected Term	Weighted Avg. Grant Date Fair Value
2017	$	127.51	24.7	%	1.9	%	3 Years	$	119.88
2016	$	113.69	25.6	%	1.4	%	3 Years	$	104.93
2015	$	97.48	23.3	%	1.3	%	3 Years	$	87.61

Schedule of Activity Related to Employee and Non-Employee Restricted Stock

Activity related to both employee and non-employee restricted stock for the year ended December 31, 2017 is as follows (in thousands, except per share amounts):



	Shares		Weighted Average Grant Date Fair Value/Share
RESTRICTED STOCK AT DECEMBER 31, 2016	224		$	102.37
Shares granted	81		123.39
Shares vested	(62	)	106.06
Shares forfeited	(4	)	104.54
RESTRICTED STOCK AT DECEMBER 31, 2017	239		$	108.51

Summary of Stock Appreciation Rights

Activity related to SARs for the year ended December 31, 2017 is as follows (in thousands, except per share amounts):



	Number of Rights		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value
OUTSTANDING AT DECEMBER 31, 2016	1,811		$	94.51
Granted	432		127.28
Exercised	(191	)	70.78
Forfeited	(9	)	107.39
Canceled	(1	)	97.48
OUTSTANDING AT DECEMBER 31, 2017	2,042		$	103.59	7.4 Years	$	64,841
EXERCISABLE AT DECEMBER 31, 2017	1,241		$	93.89	6.2 Years	$	51,420

Summary of the Weighted-Average Assumption Used in Estimating Fair Value of Stock Appreciation Rights

The following table summarizes the weighted-average assumptions used in estimating the fair value of the SARs granted during the years 2017, 2016 and 2015:



Grant Date	Expected Dividend Yield		Expected Volatility		Risk Free Interest Rate		Expected Term	Weighted Avg. Grant Date Fair Value of 1 SAR
2017	2.6	%	18.0	%	2.2	%	5.5 Years	$	17.45
2016	2.6	%	22.3	%	1.9	%	5.5 Years	$	18.76
2015	2.7	%	22.7	%	1.7	%	5.5 Years	$	16.05

Summary of Performance Shares Valuation

The following table summarizes the related assumptions used to determine the fair values of the performance share awards with a market condition granted during the years 2017, 2016 and 2015:



Grant Date	Stock Price on Measurement Date		Dividend Yield		Expected Volatility		Risk Free Interest Rate		Expected Term	Weighted Avg. Grant Date Fair Value
2017	$	127.51	2.4	%	24.7	%	1.9	%	3 Years	$	142.89
2016	$	113.69	2.5	%	25.6	%	1.4	%	3 Years	$	126.65
2015	$	97.48	2.6	%	23.3	%	1.3	%	3 Years	$	105.77

Summary of the Attributes of the Performance Shares Granted During the Period

The following table summarizes the attributes of the performance shares outstanding at December 31, 2017:



Grant Date	Shares Outstanding at 12/31/2017	Fair Value	Performance Period	Payout Range
2017	24,675	118.55	Jan 2018-Dec 2020	0-250%
2016	28,524	105.48	Jan 2017-Dec 2019	0-250%
2015	31,024	97.48	Jan 2016-Dec 2018	0-250%
2014	23,688	106.44	Jan 2015-Dec 2017	0-250%

Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Schedule of Earnings Per Share

The following table sets forth the computation of earnings per share for the three years ended December 31 (in millions, except per share amounts):



	2017			2016			2015
Numerator:
Net income attributable to Hubbell	$	243.1		$	293.0		$	277.3
Less: Earnings allocated to participating securities	(0.8		)	(0.9		)	(0.7		)
Net income available to common shareholders	$	242.3		$	292.1		$	276.6
Denominator:
Average number of common shares outstanding	54.8			55.5			57.7
Potential dilutive shares	0.3			0.2			0.3
Average number of diluted shares outstanding	55.1			55.7			58.0
Earnings per share:
Basic	$	4.42		$	5.26		$	4.79
Diluted	$	4.39		$	5.24		$	4.77

Accumulated Other Comprehensive Loss (Tables)

12 Months Ended

Dec. 31, 2017

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Summary of the Changes in Accumulated Other Comprehensive Loss (Net of Tax)

A summary of the changes in Accumulated other comprehensive loss (net of tax) for the three years ended December 31, 2017 is provided below (in millions):



(Debit) credit	Cash Flow Hedge (Loss) Gain			Unrealized Gain (Loss) on Available-for-Sale Securities			Pension and Post Retirement Benefit Plan Adjustment			Cumulative Translation Adjustment			Total
BALANCE AT DECEMBER 31, 2014	$	—		$	0.3		$	(124.7	)	$	(39.9	)	$	(164.3	)
Other comprehensive income (loss) before Reclassifications	1.7			(0.3		)	(22.5		)	(45.5		)	(66.6		)
Amounts reclassified from accumulated other comprehensive loss	(0.3		)	—			7.0			—			6.7
Current period other comprehensive income (loss)	1.4			(0.3		)	(15.5		)	(45.5		)	(59.9		)
BALANCE AT DECEMBER 31, 2015	$	1.4		$	—		$	(140.2	)	$	(85.4	)	$	(224.2	)
Other comprehensive income (loss) before Reclassifications	(1.4		)	(1.2		)	(48.5		)	(35.4		)	(86.5		)
Amounts reclassified from accumulated other comprehensive loss	—			—			8.2			—			8.2
Current period other comprehensive income (loss)	(1.4		)	(1.2		)	(40.3		)	(35.4		)	(78.3		)
BALANCE AT DECEMBER 31, 2016	$	—		$	(1.2	)	$	(180.5	)	$	(120.8	)	$	(302.5	)
Other comprehensive income (loss) before Reclassifications	(1.7		)	0.6			(3.4		)	28.9			24.4
Amounts reclassified from accumulated other comprehensive loss	0.9			—			7.4			—			8.3
Current period other comprehensive income (loss)	(0.8		)	0.6			4.0			28.9			32.7
BALANCE AT DECEMBER 31, 2017	$	(0.8	)	$	(0.6	)	$	(176.5	)	$	(91.9	)	$	(269.8	)

Summary of the Gain (Loss) Reclassifications Out of Accumulated Other Comprehensive Loss

A summary of the gain (loss) reclassifications out of Accumulated other comprehensive loss for the two years ended December 31 is provided below (in millions):



Details about Accumulated Other Comprehensive Loss Components	2017				2016				Location of Gain (Loss) Reclassified into Income
Cash flow hedges gain (loss):
Forward exchange contracts	$	(0.4	)		$	(0.3	)		Net Sales
	(0.9		)		0.3				Cost of goods sold
	(1.3		)		—				Total before tax
	0.4				—				Tax (expense) benefit
	$	(0.9	)		$	—			Gain (loss) net of tax
Amortization of defined benefit pension and post retirement benefit items:
Prior-service costs	$	0.9		^(a)	$	0.9		^(a)
Actuarial gains/(losses)	(11.4		)	^(a)	(13.9		)	^(a)
Settlement and curtailment losses	(0.4		)	^(a)	—			^(a)
	(10.9		)		(13.0		)		Total before tax
	3.5				4.8				Tax benefit (expense)
	$	(7.4	)		$	(8.2	)		(Loss) gain net of tax
Losses reclassified into earnings	$	(8.3	)		$	(8.2	)		(Loss) gain net of tax


(a)	These accumulated other comprehensive loss components are included in the computation of net periodic pension cost (see Note 10 — Retirement Benefits for additional details).

Industry Segments and Geographic Area Information (Tables)

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Summary of Industry Segment Data

INDUSTRY SEGMENT DATA



	2017			2016			2015
Net Sales:
Electrical	$	2,532.8		$	2,460.2		$	2,388.3
Power	1,136.0			1,045.0			1,002.1
TOTAL NET SALES	$	3,668.8		$	3,505.2		$	3,390.4
Operating Income:
Electrical	$	282.5		$	267.4		$	279.0
Power	221.2			210.4			195.6
Operating Income	$	503.7		$	477.8		$	474.6
Interest expense	(44.9		)	(43.4		)	(31.0		)
Loss on extinguishment of debt	(10.1		)	—			—
Investment income and other expense, net	(5.6		)	(4.0		)	(25.0		)
INCOME BEFORE INCOME TAXES	$	443.1		$	430.4		$	418.6
Assets:
Electrical	$	2,344.7		$	2,246.0		$	2,120.9
Power	1,102.2			911.5			839.7
General Corporate	273.7			367.5			248.1
TOTAL ASSETS	$	3,720.6		$	3,525.0		$	3,208.7
Capital Expenditures:
Electrical	$	48.0		$	43.4		$	47.9
Power	29.0			22.7			28.4
General Corporate	2.7			1.1			0.8
TOTAL CAPITAL EXPENDITURES	$	79.7		$	67.2		$	77.1
Depreciation and Amortization:
Electrical	$	65.7		$	61.2		$	56.2
Power	34.1			31.1			29.0
TOTAL DEPRECIATION AND AMORTIZATION	$	99.8		$	92.3		$	85.2

Summary of Product Class Data

PRODUCT CLASS DATA



	2017		2016		2015
Net Sales:
Electrical Systems	$	1,597.1	$	1,514.4	$	1,476.7
Lighting	935.7		945.8		911.6
Power	1,136.0		1,045.0		1,002.1
TOTAL NET SALES	$	3,668.8	$	3,505.2	$	3,390.4

Summary of Geographic Area Data

GEOGRAPHIC AREA DATA



	2017		2016		2015
Net Sales:
United States	$	3,280.9	$	3,147.4	$	3,008.4
International	387.9		357.8		382.0
TOTAL NET SALES	$	3,668.8	$	3,505.2	$	3,390.4
Operating Income:
United States	$	422.1	$	419.1	$	426.1
International	81.6		58.7		48.5
TOTAL OPERATING INCOME	$	503.7	$	477.8	$	474.6
Long-lived Assets:
United States	$	1,877.4	$	1,762.9	$	1,627.7
International	232.8		200.1		187.1
TOTAL LONG-LIVED ASSETS	$	2,110.2	$	1,963.0	$	1,814.8

Guarantees (Tables)

12 Months Ended

Dec. 31, 2017

Standard Product Warranty Disclosure [Abstract]

Summary of Changes in the Accrued Product Warranties

Changes in the accrual for product warranties in 2017 are set forth below (in millions):



BALANCE AT DECEMBER 31, 2015	$	13.2
Provision	9.7
Expenditures/other	(9.1		)
BALANCE AT DECEMBER 31, 2016	$	13.8
Provision	10.0
Expenditures/other	(9.8		)
BALANCE AT DECEMBER 31, 2017	$	14.0

Restructuring Costs (Tables)

12 Months Ended

Dec. 31, 2017

Restructuring and Related Activities [Abstract]

Summary of Restructuring Costs



Year Ended December 31, 2015	Cost of goods sold		Selling & administrative expense		Total
Electrical Segment	$	14.5	$	7.2	$	21.7
Power Segment	0.8		1.1		1.9
Total 2015 Restructuring Costs	$	15.3	$	8.3	$	23.6

Year Ended December 31, 2016
Electrical Segment	$	27.3	$	6.6	$	33.9
Power Segment	0.2		0.9		1.1
Total 2016 Restructuring Costs	$	27.5	$	7.5	$	35.0

Year Ended December 31, 2017
Electrical Segment	$	11.5	$	5.4	$	16.9
Power Segment	2.2		1.2		3.4
Total 2017 Restructuring Costs	$	13.7	$	6.6	$	20.3

Schedule of Restructuring Reserve by Type of Cost

The actual and expected costs for our restructuring actions are as follows (in millions):



	Expected Costs		Costs incurred in 2015		Costs incurred in 2016		Costs incurred in 2017		Remaining costs at 12/31/17
2017 Restructuring Actions
Electrical Segment	$	13.0	$	—	$	—	$	10.6	$	2.4
Power Segment	3.9		—		—		3.4		0.5
Total 2017 Restructuring Actions	$	16.9	$	—	$	—	$	14.0	$	2.9
2016 Restructuring Actions
Electrical Segment	$	35.4	$	—	$	30.7	$	3.8	$	0.9
Power Segment	1.3		—		1.1		—		0.2
Total 2016 Restructuring Actions	$	36.7	$	—	$	31.8	$	3.8	$	1.1
2015 Restructuring Actions
Electrical Segment	$	23.0	$	17.3	$	3.2	$	2.5	$	—
Power Segment	1.9		1.9		—		—		—
Total 2015 and Prior Restructuring Actions	$	24.9	$	19.2	$	3.2	$	2.5	$	—
Total Restructuring Actions	$	78.5	$	19.2	$	35.0	$	20.3	$	4.0

The following table summarizes the accrued liabilities for our restructuring actions (in millions):



	Beginning Accrued Restructuring Balance 1/1/17		Pre-tax Restructuring Costs			Utilization and Foreign Exchange			Ending Accrued Restructuring Balance 12/31/2017
2017 Restructuring Actions
Severance	$	—	$	7.4		$	(3.8	)	$	3.6
Asset write-downs	—		0.5			(0.5		)	—
Facility closure and other costs	—		6.1			(4.3		)	1.8
Total 2017 Restructuring Actions	$	—	$	14.0		$	(8.6	)	$	5.4
2016 and Prior Restructuring Actions
Severance	$	10.4	$	(2.2	)	$	(6.4	)	$	1.8
Asset write-downs	—		—			—			—
Facility closure and other costs ^(a)	14.1		8.5			(8.9		)	13.7
Total 2016 and Prior Restructuring Actions	$	24.5	$	6.3		$	(15.3	)	$	15.5
Total Restructuring Actions	$	24.5	$	20.3		$	(23.9	)	$	20.9

Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Summary of Quarterly Financial Data

The table below sets forth summarized quarterly financial data for the years ended December 31, 2017 and 2016 (in millions, except per share amounts):



	Reported First Quarter		Reported Second Quarter		Reported Third Quarter		Fourth Quarter
2017
Net sales	$	852.3	$	948.3	$	950.5	$	917.7
Cost of goods sold	$	590.5	$	653.6	$	643.6	$	629.2
Gross profit	$	261.8	$	294.7	$	306.9	$	288.5
Selling & administrative expenses	$	157.7	$	164.1	$	160.5	$	165.8
Net income ⁽¹⁾	$	63.9	$	80.8	$	82.8	$	22.4
Net Income attributable to Hubbell ⁽¹⁾	$	62.8	$	79.1	$	80.8	$	20.4
Earnings per share — Basic	$	1.13	$	1.44	$	1.47	$	0.37
Earnings per share — Diluted	$	1.13	$	1.43	$	1.47	$	0.37
⁽¹⁾ Net income in the fourth quarter of 2017 includes approximately $57 million, or $1.02 per share, impact associated with the TCJA.
	Reported First Quarter		Reported Second Quarter		Reported Third Quarter		Fourth Quarter
2016
Net sales	$	834.8	$	908.8	$	907.4	$	854.2
Cost of goods sold	$	574.9	$	615.3	$	618.7	$	595.6
Gross profit	$	259.9	$	293.5	$	288.7	$	258.6
Selling & administrative expenses	$	158.0	$	161.4	$	152.7	$	150.8
Net income	$	62.0	$	82.0	$	88.1	$	65.7
Net Income attributable to Hubbell	$	60.9	$	81.0	$	86.7	$	64.4
Earnings per share — Basic	$	1.08	$	1.46	$	1.56	$	1.16
Earnings per share — Diluted	$	1.08	$	1.45	$	1.56	$	1.16

Significant Accounting Policies (Details) - USD ($)	12 Months Ended
Significant Accounting Policies (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of LIFO inventory	71.00%
Capitalized Computer Software, Net [Abstract]
Capitalized computer software costs, net of amortization	$ 15,700,000	$ 15,600,000
Amortization expense	$ 5,600,000	5,200,000	$ 4,600,000
Goodwill Annual Impairment Test [Abstract]
Gross value of definite-lived intangible assets following accelerated amortization method (as a percentage)	60.00%
Impairment of intangible assets, finite-lived	$ 0	0	0
Impairment of intangible assets, indefinite-lived (excluding goodwill)	$ 0	$ 0	$ 0
Research and development expense as a percentage of cost of goods sold	3.00%	2.00%	2.00%
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Operating income	$ 503,700,000	$ 477,800,000	$ 474,600,000
Other expense, net	(6,500,000)	(4,500,000)	$ (25,500,000)
Pro Forma \| Accounting Standards Update 2017-07
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Operating income	15,000,000	12,000,000
Other expense, net	0	$ 0
Pro Forma \| Accounting Standards Update 2016-02
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Lease, right-of-use asset (less than)	$ 100,000,000
Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Customer returns as a percentage of gross sales	1.00%
Goodwill Annual Impairment Test [Abstract]
Useful life, intangible assets	5 years
Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Customer returns as a percentage of gross sales	2.00%
Goodwill Annual Impairment Test [Abstract]
Useful life, intangible assets	30 years
Capitalized Computer Software Costs
Capitalized Computer Software, Net [Abstract]
Depreciable lives	5 years

Business Acquisitions - Narrative (Details)		1 Months Ended	3 Months Ended			12 Months Ended
Business Acquisitions - Narrative (Details)	Feb. 02, 2018 USD ($)	Feb. 15, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($) acquisition	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jan. 31, 2018 USD ($)
Business Acquisition [Line Items]
Goodwill			$ 1,089,000,000			$ 1,089,000,000	$ 991,000,000	$ 928,500,000
Payments to acquire businesses, net of cash acquired						184,100,000	$ 173,400,000	$ 163,400,000
Power
Business Acquisition [Line Items]
Number of businesses acquired \| acquisition					2
Consideration transferred to acquire business					$ 10,100,000
Intangible assets acquired					3,400,000
Goodwill					5,000,000
Goodwill, expected to be tax deductible					$ 2,700,000
Intangible assets, useful life					13 years
iDevices, LLC
Business Acquisition [Line Items]
Consideration transferred to acquire business				$ 59,200,000
Intangible assets acquired				9,600,000
Goodwill				$ 45,900,000
Intangible assets, useful life				12 years
Advance Engineering Corporation and Perfect Pipe & Supply Corporation
Business Acquisition [Line Items]
Consideration transferred to acquire business				$ 32,500,000
Intangible assets acquired				16,800,000
Goodwill				$ 12,800,000
Intangible assets, useful life				18 years
Meramec Instrument Transformer Company
Business Acquisition [Line Items]
Consideration transferred to acquire business			69,700,000
Intangible assets acquired			33,800,000			33,800,000
Goodwill			$ 24,800,000			$ 24,800,000
Intangible assets, useful life			21 years
Subsequent Event \| Aclara
Business Acquisition [Line Items]
Consideration transferred to acquire business	$ 1,100,000,000	$ 1,100,000,000
Term Loan Agreement \| Line of Credit \| Subsequent Event
Business Acquisition [Line Items]
Line of credit, maximum borrowing capacity	500,000,000								$ 500,000,000
Notes 2028 Term \| Senior Notes \| Subsequent Event
Business Acquisition [Line Items]
Face amount	$ 450,000,000

Business Acquisitions (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill	$ 1,089.0	$ 991.0	$ 928.5
Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Tangible assets acquired	34.4
Intangible assets	63.6
Goodwill	88.5
Net deferred taxes	(0.2)
Other liabilities assumed	(14.8)
TOTAL CONSIDERATION, NET OF CASH RECEIVED	$ 171.5

Receivables and Allowances (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable, Net, Current [Abstract]
Trade accounts receivable	$ 576.3	$ 565.5
Non-trade receivables	19.1	15.1
Accounts receivable, gross	595.4	580.6
Allowance for credit memos, returns and cash discounts	(50.5)	(45.9)
Allowance for doubtful accounts	(4.6)	(4.7)
Total allowances	(55.1)	(50.6)
ACCOUNTS RECEIVABLE, NET	$ 540.3	$ 530.0

Inventory (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw material	$ 190.0	$ 162.7
Work-in-process	115.8	102.8
Finished goods	390.5	327.9
Inventory, gross	696.3	593.4
Excess of FIFO over LIFO cost basis	(61.6)	(61.0)
INVENTORIES, NET	$ 634.7	$ 532.4

Goodwill and Other Intangible Assets Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Goodwill, beginning of period	$ 991.0	$ 928.5
Current year acquisitions	88.5	70.0
Foreign currency translation and prior year acquisitions	9.5	(7.5)
Goodwill, end of period	1,089.0	991.0
Electrical
Goodwill [Roll Forward]
Goodwill, beginning of period	652.0	611.2
Current year acquisitions	58.7	49.4
Foreign currency translation and prior year acquisitions	6.9	(8.6)
Goodwill, end of period	717.6	652.0
Power
Goodwill [Roll Forward]
Goodwill, beginning of period	339.0	317.3
Current year acquisitions	29.8	20.6
Foreign currency translation and prior year acquisitions	2.6	1.1
Goodwill, end of period	$ 371.4	$ 339.0

Goodwill and Other Intangible Assets Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill acquired	$ 88.5	$ 70.0
Year to date amortization expense	34.9	$ 32.3	$ 28.2
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Amortization expense, 2018	35.7
Amortization expense, 2019	33.2
Amortization expense, 2020	33.8
Amortization expense, 2021	33.2
Amortization expense, 2022	$ 31.7

Other Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Other Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 613.4	$ 549.6
Accumulated Amortization	(206.8)	(171.4)
TOTAL INTANGIBLE ASSETS	667.2	602.9
Tradenames and other
Other Intangible Assets [Line Items]
Indefinite-lived intangible assets (excluding goodwill)	53.8	53.3
Patents, tradenames and trademarks
Other Intangible Assets [Line Items]
Finite-lived intangible assets, gross	151.4	143.7
Accumulated Amortization	(50.1)	(43.4)
Customer/agent relationships and other
Other Intangible Assets [Line Items]
Finite-lived intangible assets, gross	462.0	405.9
Accumulated Amortization	$ (156.7)	$ (128.0)

Investments - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Investments - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available for sale investments	$ 58.4	$ 57.4
Payments to acquire available-for-sale securities	20.9	20.0	$ 24.5
Unrealized gain/(loss) on available-for-sale securities, net of tax	0.6	(0.9)
Unobservable inputs for which little or no market data exists (Level 3)
Schedule of Available-for-sale Securities [Line Items]
Available for sale investments	4.1	$ 3.8
Payments to acquire available-for-sale securities	5.0
Municipal Bonds
Schedule of Available-for-sale Securities [Line Items]
Available for sale investments	$ 54.3

Investments - Amortized Cost Basis (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Available-for-sale Securities [Abstract]
Available-for-sale securities, amortized cost	$ 59.3	$ 58.6
Available-for-sale securities, accumulated gross unrealized gains	0.1	0.3
Available-for-sale securities, accumulated gross unrealized losses	(1.0)	(1.5)
Available-for-sale debt securities	58.4	57.4
Trading Securities [Abstract]
Trading securities, amortized cost	8.9	7.1
Trading securities, accumulated gross unrealized gains	4.9	3.1
Trading securities, accumulated gross unrealized losses	0.0	0.0
Trading securities	13.8	10.2
Investments, amortized cost	68.2	65.7
Investments, accumulated unrealized gains	5.0	3.4
TOTAL INVESTMENTS	$ 72.2	$ 67.6

Investments - Contractual Maturity (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Amortized Cost [Abstract]
Amortized Cost Due within 1 year	$ 14.5
Amortized Cost After 1 year but within 5 years	31.5
Amortized Cost After 5 years but within 10 years	10.9
Amortized Cost Due after 10 years	2.4
Available-for-sale securities, amortized cost	59.3	$ 58.6
Fair Value [Abstract]
Fair Value Due within 1 year	14.5
Fair Value After 1 year but within 5 years	30.7
Fair Value After 5 years but within 10 years	10.8
Fair Value Due after 10 years	2.4
Available for Sale	$ 58.4	$ 57.4

Property, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant, and Equipment [Line Items]
Gross property, plant, and equipment	$ 1,161.8	$ 1,133.4
Less accumulated depreciation	(703.5)	(693.6)
NET PROPERTY, PLANT, AND EQUIPMENT	458.3	439.8
Depreciation	57.5	53.4	$ 51.2
Land
Property, Plant, and Equipment [Line Items]
Gross property, plant, and equipment	40.0	43.1
Buildings and improvements
Property, Plant, and Equipment [Line Items]
Gross property, plant, and equipment	$ 272.2	268.7
Buildings and improvements \| Minimum
Property, Plant, and Equipment [Line Items]
Depreciable lives	20 years
Buildings and improvements \| Maximum
Property, Plant, and Equipment [Line Items]
Depreciable lives	45 years
Machinery, tools, and equipment
Property, Plant, and Equipment [Line Items]
Gross property, plant, and equipment	$ 806.2	784.7
Machinery, tools, and equipment \| Minimum
Property, Plant, and Equipment [Line Items]
Depreciable lives	3 years
Machinery, tools, and equipment \| Maximum
Property, Plant, and Equipment [Line Items]
Depreciable lives	15 years
Construction-in-progress
Property, Plant, and Equipment [Line Items]
Gross property, plant, and equipment	$ 43.4	$ 36.9

Other Accrued Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Accrued Liabilities [Abstract]
Customer program incentives	$ 41.2	$ 41.2
Accrued income taxes	27.5	8.4
Deferred revenue	10.2	11.8
Other	96.0	94.8
TOTAL	$ 174.9	$ 156.2

- Definition

The carrying amount of consideration received or receivable as of the balance sheet date on potential earnings that were not recognized as revenue in conformity with GAAP, and which are expected to be recognized as such within one year or the normal operating cycle, if longer, including sales, license fees, and royalties, but excluding interest income.

+ References + Details

Other Non-Current Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Other Liabilities, Noncurrent [Abstract]
Pensions	$ 213.2	$ 208.3
Other post-employment benefits	24.6	24.0
Deferred tax liabilities	23.7	41.2
Other	118.0	68.2
TOTAL	$ 379.5	$ 341.7

Retirement Benefits - Narrative (Details)	3 Months Ended	12 Months Ended
Retirement Benefits - Narrative (Details)	Dec. 31, 2016 USD ($) benefit_plan	Dec. 31, 2017 USD ($) benefit_plan	Dec. 31, 2016 USD ($) benefit_plan	Dec. 31, 2015 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 876,200,000	$ 924,600,000	$ 876,200,000
Number of defined contribution pension plans (benefit plan) \| benefit_plan		6
Defined contribution pension plans, total costs		$ 19,800,000	$ 15,600,000	$ 13,300,000
Number of multiemployer defined benefit pension plans (benefit_plan) \| benefit_plan	2		2
Number of multiemployer plans withdrawn from \| benefit_plan		1
Multiemployer plan total employer contributions		$ 400,000	$ 500,000	800,000
Pre-tax restructuring costs		20,300,000	35,000,000	23,600,000
Expected cost remaining		4,000,000
Employer stock included in plan assets	$ 40,000,000	0	$ 40,000,000
Employer stock as percentage of plan assets	6.60%		6.60%
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service cost (credit)		100,000	$ 100,000	200,000
Benefit obligation	$ 917,400,000	$ 956,100,000	$ 917,400,000	$ 912,300,000
Discount rate	4.12%	3.67%	4.12%	4.71%
Employer contributions		$ 9,800,000	$ 24,300,000
Withdrawal from Multiemployer Defined Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Pre-tax restructuring costs	$ 12,500,000
Expected cost remaining		$ 23,000,000
U.S. Defined Benefit Pension Plan \| Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Curtailment gain			34,100,000
Amortization of prior service cost (credit)			200,000
Projected benefit obligation settled			$ 40,000,000
Voluntary lump sum program payment				$ 27,700,000
Defined benefit obligation per plan, as a percent of total benefit obligation		88.00%
Discount rate	4.30%	3.80%	4.30%
Effect on defined benefit obligation, due to change in mortality table utilized		$ 15,000,000
Estimated future employer contributions in next fiscal year		$ 1,900,000
Foreign Plan \| Canada
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.85%	3.50%	3.85%
Foreign Plan \| United Kingdom
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.70%	2.60%	2.70%

Retirement Benefits - Change in Benefit Obligations and Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in plan assets
Prepaid pensions (included in Other long-term assets)	$ 51.1	$ 55.0
Pension Benefits
Change in benefit obligation
Benefit obligation at beginning of year	917.4	912.3
Service cost	5.9	12.9	$ 17.7
Interest cost	37.2	41.9	40.5
Plan participants’ contributions	0.6	0.5
Amendments	0.3	(34.1)
Actuarial loss	29.7	88.0
Currency impact	9.7	(18.5)
Other	(0.4)	(0.5)
Benefits paid	(44.3)	(85.1)
Benefit obligation at end of year	956.1	917.4	912.3
Change in plan assets
Fair value of plan assets at beginning of year	705.1	757.6
Actual return on plan assets	58.6	23.6
Employer contributions	9.8	24.3
Plan participants’ contributions	0.6	0.5
Currency impact	9.0	(15.8)
Benefits paid	(44.3)	(85.1)
Fair value of plan assets at end of year	738.8	705.1	757.6
FUNDED STATUS	(217.3)	(212.3)
Prepaid pensions (included in Other long-term assets)	1.5	1.7
Accrued benefit liability (short-term and long-term)	(218.8)	(214.0)
NET AMOUNT RECOGNIZED IN THE CONSOLIDATED BALANCE SHEET	(217.3)	(212.3)
Amounts recognized in Accumulated other comprehensive loss (income) consist of:
Net actuarial loss	270.1	274.2
Prior service cost (credit)	0.6	0.4
NET AMOUNT RECOGNIZED IN ACCUMULATED OTHER COMPREHENSIVE LOSS	270.7	274.6
Other Benefits
Change in benefit obligation
Benefit obligation at beginning of year	26.2	26.6
Service cost	0.1	0.0	0.1
Interest cost	1.0	1.2	1.0
Plan participants’ contributions	0.0	0.0
Amendments	0.0	0.0
Actuarial loss	1.4	0.2
Currency impact	0.0	0.0
Other	0.0	0.0
Benefits paid	(1.7)	(1.8)
Benefit obligation at end of year	27.0	26.2	$ 26.6
Change in plan assets
Employer contributions	1.7	1.8
Benefits paid	(1.7)	(1.8)
FUNDED STATUS	(27.0)	(26.2)
Accrued benefit liability (short-term and long-term)	(27.0)	(26.2)
NET AMOUNT RECOGNIZED IN THE CONSOLIDATED BALANCE SHEET	(27.0)	(26.2)
Amounts recognized in Accumulated other comprehensive loss (income) consist of:
Net actuarial loss	3.0	1.7
Prior service cost (credit)	(2.3)	(3.3)
NET AMOUNT RECOGNIZED IN ACCUMULATED OTHER COMPREHENSIVE LOSS	$ 0.7	$ (1.6)

Retirement Benefits - Accumulated Benefit Obligation In Excess of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Projected benefit obligation	$ 842.7	$ 801.1
Accumulated benefit obligation	826.5	781.4
Fair value of plan assets	$ 626.3	$ 603.1

Retirement Benefits - Components of Pension and Other Benefit Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension Benefits
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 5.9	$ 12.9	$ 17.7
Interest cost	37.2	41.9	40.5
Expected return on plan assets	(34.1)	(44.3)	(53.2)
Amortization of prior service cost (credit)	0.1	0.1	0.2
Amortization of actuarial losses (gains)	11.4	13.9	12.1
Curtailment and settlement losses	0.4	0.2	0.0
Net periodic benefit cost	20.9	24.7	17.3
Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, after Tax [Abstract]
Current year net actuarial loss	4.2	72.0	37.0
Current year prior service credit	0.3	0.0	0.0
Amortization of prior service (cost) credit	(0.1)	(0.1)	(0.2)
Amortization of net actuarial (losses) gains	(11.4)	(13.9)	(12.1)
Currency impact	3.5	(4.0)	(0.1)
Other adjustments	(0.4)	(0.2)	0.0
Total recognized in other comprehensive loss	(3.9)	53.8	24.6
Defined Benefit Plan, Amount Recognized in Net Periodic Benefit Cost (Credit) and Other Comprehensive (Income) Loss, before Tax	17.0	78.5	41.9
Defined Benefit Plan, Expected Amortization, Next Fiscal Year [Abstract]
Amortization of prior service cost (credit)	0.1
Amortization of net loss	10.9
TOTAL EXPECTED TO BE RECOGNIZED THROUGH INCOME DURING NEXT FISCAL YEAR	11.0
Other Benefits
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	0.1	0.0	0.1
Interest cost	1.0	1.2	1.0
Expected return on plan assets		0.0	0.0
Amortization of prior service cost (credit)	(1.0)	(1.0)	(1.0)
Amortization of actuarial losses (gains)	0.0	0.0	(0.1)
Curtailment and settlement losses	0.0	0.0	0.0
Net periodic benefit cost	0.1	0.2	0.0
Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, after Tax [Abstract]
Current year net actuarial loss	1.4	0.2	0.5
Current year prior service credit		0.0	0.0
Amortization of prior service (cost) credit	1.0	1.0	1.0
Amortization of net actuarial (losses) gains	0.0	0.0	0.1
Currency impact	0.0	0.0	0.0
Other adjustments	0.0	0.0	0.0
Total recognized in other comprehensive loss	2.4	1.2	1.6
Defined Benefit Plan, Amount Recognized in Net Periodic Benefit Cost (Credit) and Other Comprehensive (Income) Loss, before Tax	2.5	$ 1.4	$ 1.6
Defined Benefit Plan, Expected Amortization, Next Fiscal Year [Abstract]
Amortization of prior service cost (credit)	(1.0)
Amortization of net loss	0.2
TOTAL EXPECTED TO BE RECOGNIZED THROUGH INCOME DURING NEXT FISCAL YEAR	$ (0.8)

Retirement Benefits - Projected Benefit Obligation Assumptions (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.67%	4.12%	4.71%
Rate of compensation increase	3.24%	3.55%	3.59%
Discount rate	4.12%	4.71%	4.23%
Expected return on plan assets	4.94%	6.04%	6.36%
Rate of compensation increase	3.55%	3.59%	3.15%
Other Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.70%	4.10%	4.60%
Rate of compensation increase	4.00%	3.93%	3.92%
Discount rate	4.10%	4.60%	4.10%
Rate of compensation increase	3.93%	3.92%	3.60%

Retirement Benefits - Assumed Health Care Cost Trend Rates (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Health care cost trend assumed for next year	7.00%	7.20%	7.40%
Rate to which the cost trend is assumed to decline	5.00%	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	2028	2028	2028

Retirement Benefits - One-Percentage-Point Change in Assumed Health Care Cost Trend Rates (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Effect on total of service and interest cost, one percentage point increase	$ 0.1
Effect on total of service and interest cost, one percentage point decrease	(0.1)
Effect of on postretirement benefit obligation, one percentage point increase	1.8
Effect on postretirement benefit obligation, one percentage point decrease	$ (1.5)

Retirement Benefits - Combined Targeted and Actual Domestic and Foreign Pension Plans Weighted Average Asset Allocation (Details)	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Percentage of plan assets, target	100.00%
Percentage of plan assets, actual	100.00%	100.00%
Equity securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Percentage of plan assets, target	19.00%
Percentage of plan assets, actual	18.00%	16.00%
Debt securities & Cash
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Percentage of plan assets, target	64.00%
Percentage of plan assets, actual	65.00%	65.00%
Alternative Investments
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Percentage of plan assets, target	17.00%
Percentage of plan assets, actual	17.00%	19.00%

Retirement Benefits - Estimated Future Benefit Payments (Details) $ in Millions	Dec. 31, 2017 USD ($)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
2018	$ 42.9
2019	44.4
2020	46.1
2021	47.6
2022	49.8
2023-2027	267.2
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
2018	2.4
2019	2.3
2020	2.2
2021	2.2
2022	2.0
2023-2027	$ 8.8

Debt Summary of Long-term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2017	Sep. 30, 2017	Aug. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Nov. 30, 2010
Debt Instrument [Line Items]
Long-term Debt	$ 987.1			$ 990.5
Notes 2018 Term \| Senior Notes
Debt Instrument [Line Items]
Long-term Debt	$ 0.0			$ 299.3
Interest rate, stated percentage		5.95%		5.95%
Notes 2022 Term \| Senior Notes
Debt Instrument [Line Items]
Long-term Debt	$ 297.9			$ 297.5
Interest rate, stated percentage	3.625%			3.625%		3.625%
Notes 2026 Term \| Senior Notes
Debt Instrument [Line Items]
Long-term Debt	$ 394.4			$ 393.7
Interest rate, stated percentage	3.35%			3.35%	3.35%
Notes 2027 Term \| Senior Notes
Debt Instrument [Line Items]
Long-term Debt	$ 294.8
Interest rate, stated percentage	3.15%		3.15%

Debt Other Information Related to Short-term Debt (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
Interest rate at year end	1.95%	6.89%
Interest rate paid during the year (weighted average)	2.24%	0.72%

Debt Narrative (Details) - USD ($)				1 Months Ended				12 Months Ended
Debt Narrative (Details) - USD ($)	Feb. 02, 2018	Jan. 31, 2018	Dec. 16, 2015	Sep. 30, 2017	Aug. 31, 2017	Mar. 31, 2016	Nov. 30, 2010	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Loss on extinguishment of debt								$ 10,100,000	$ 0	$ 0
Short-term debt								68,100,000	3,200,000
Commercial paper								63,000,000	0
Line of credit outstanding, current portion								5,100,000	3,200,000
Interest and fees paid								47,900,000	37,100,000	29,500,000
Make whole payment for extinguishment of debt								300,000,000	0	$ 0
Other LOC
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity								53,900,000	51,400,000
Line of credit outstanding, current portion								$ 21,500,000	$ 21,000,000
Notes 2022 Term Interest Rate Lock
Debt Instrument [Line Items]
Loss on forward interest rate lock, recorded in accumulated other comprehensive loss							$ 1,600,000
Senior Notes \| Notes 2027 Term
Debt Instrument [Line Items]
Face amount					$ 300,000,000
Interest rate, stated percentage					3.15%			3.15%
Proceeds from debt, net of issuance costs					$ 294,600,000
Senior Notes \| Notes 2018 Term
Debt Instrument [Line Items]
Interest rate, stated percentage				5.95%					5.95%
Debt instrument, repurchase amount				$ 300,000,000
Loss on extinguishment of debt				$ 10,100,000
Make whole payment for extinguishment of debt								$ 9,900,000
Senior Notes \| Notes 2026 Term
Debt Instrument [Line Items]
Face amount						$ 400,000,000
Interest rate, stated percentage						3.35%		3.35%	3.35%
Proceeds from issuance of long-term debt						$ 393,400,000
Senior Notes \| Notes 2022 Term
Debt Instrument [Line Items]
Face amount							$ 300,000,000
Interest rate, stated percentage							3.625%	3.625%	3.625%
Senior Notes \| Notes 2028 Term \| Subsequent Event
Debt Instrument [Line Items]
Face amount	$ 450,000,000
Interest rate, stated percentage	3.50%
Proceeds from issuance of long-term debt	$ 442,600,000
Line of Credit \| Term Loan Agreement \| Subsequent Event
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity	$ 500,000,000	$ 500,000,000
Amortization percentage, equal quarterly installments, year one	5.00%
Amortization percentage, equal quarterly installments, year two	5.00%
Amortization percentage, equal quarterly installments, year three	7.50%
Amortization percentage, equal quarterly installments, year four	10.00%
Amortization percentage, equal quarterly installments, year five	10.00%
Line of Credit \| Revolving Credit Facility \| Credit Agreement
Debt Instrument [Line Items]
Debt instrument, term			5 years
Line of credit, maximum borrowing capacity			$ 750,000,000
Line of credit facility, accordion feature, higher borrowing capacity option			$ 1,250,000,000.000
Line of credit facility covenants maximum debt to capitalization percentage			55.00%
Line of Credit \| Revolving Credit Facility \| Credit Agreement \| Subsequent Event
Debt Instrument [Line Items]
Debt instrument, term		5 years
Line of credit, maximum borrowing capacity		$ 750,000,000
Line of credit facility, accordion feature, higher borrowing capacity option		$ 1,250,000,000.000
Line of credit facility covenants maximum debt to capitalization percentage		65.00%

Income Taxes Components of Income Tax Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income before income taxes:
United States	$ 354.7	$ 349.5	$ 347.2
International	88.4	80.9	71.4
Income before income taxes	443.1	430.4	418.6
Provision for income taxes — current:
Federal	164.1	85.5	110.4
State	15.3	17.4	13.7
International	28.1	17.0	17.6
Total provision-current	207.5	119.9	141.7
Provision for income taxes — deferred:
Federal	(10.4)	13.5	(1.7)
State	(0.9)	1.3	0.4
International	(3.0)	(2.1)	(3.9)
Total provision — deferred	(14.3)	12.7	(5.2)
TOTAL PROVISION FOR INCOME TAXES	$ 193.2	$ 132.6	$ 136.5

Income Taxes Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Inventories	$ 5.2	$ 8.8
Income tax credits	21.0	30.9
Accrued liabilities	17.2	20.8
Pension	55.8	77.6
Post retirement and post employment benefits	6.5	10.0
Stock-based compensation	13.4	17.5
Net operating loss carryforwards	19.0	27.2
Miscellaneous other	10.7	7.5
Gross deferred tax assets	148.8	200.3
Valuation allowance	(19.4)	(22.6)
Total deferred tax assets, net of valuation allowance	129.4	177.7
Deferred tax liabilities:
Acquisition basis difference	(116.5)	(162.1)
Property, plant, and equipment	(30.3)	(46.3)
Total deferred tax liabilities	(146.8)	(208.4)
Non-current tax assets (included in Other long-term assets)	6.3	10.5
Non-current tax liabilities (included in Other Non-Current Liabilities)	(23.7)	(41.2)
TOTAL NET DEFERRED TAX LIABILITY	$ (17.4)	$ (30.7)

Income Taxes Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at beginning of year	$ 20.2	$ 20.3	$ 21.6
Additions based on tax positions relating to the current year	13.6	2.8	2.9
Reductions based on expiration of statute of limitations	(1.4)	(5.7)	(2.8)
Additions to tax positions relating to previous years	1.0	2.9	0.4
Settlements	(3.9)	(0.1)	(1.8)
TOTAL UNRECOGNIZED TAX BENEFITS	$ 29.5	$ 20.2	$ 20.3

Income Taxes Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	35.00%	35.00%	35.00%
State income taxes, net of federal benefit	1.20%	2.40%	2.30%
Foreign income taxes	(3.10%)	(3.40%)	(3.90%)
TCJA and related	12.80%	0.00%	0.00%
Other, net	(2.30%)	(3.20%)	(0.80%)
CONSOLIDATED EFFECTIVE INCOME TAX RATE	43.60%	30.80%	32.60%

Income Taxes Narrative (Details) $ in Millions		12 Months Ended
Income Taxes Narrative (Details) $ in Millions	Dec. 22, 2017 USD ($)	Dec. 31, 2017 USD ($) country	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Tax Credit Carryforward [Line Items]
Tax Cuts and Jobs Act of 2017, provisional income tax expense	$ 57.0
Tax Cuts and Jobs Act of 2017, undistributed accumulated earnings of foreign subsidiary		$ 720.0
Income tax credits		21.0	$ 30.9
Net operating loss carryforwards		19.0	27.2
Valuation allowance		19.4	22.6
Income taxes paid		130.8	117.4	$ 139.1
Unrecognized tax benefits timing of deductibility unknown		0.9
Unrecognized tax benefits, income tax penalties and interest expense		0.5	0.7	$ 1.2
Unrecognized tax benefits, income tax penalties and interest accrued		5.2	$ 4.8
Minimum
Tax Credit Carryforward [Line Items]
Unrecognized tax benefits that would impact effective tax rate		15.9
Significant (increase) decrease in unrecognized tax benefits is reasonably possible, estimated range of change, upper bound		1.0
Maximum
Tax Credit Carryforward [Line Items]
Unrecognized tax benefits that would impact effective tax rate		26.1
Significant (increase) decrease in unrecognized tax benefits is reasonably possible, estimated range of change, upper bound		11.8
Federal, State, and Local
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards		19.0
Tax credit carryforward indefinitely
Tax Credit Carryforward [Line Items]
Income tax credits		12.7
Net operating loss carryforwards		9.1
Carryforward Subject To Expiration
Tax Credit Carryforward [Line Items]
Income tax credits		8.3
Net operating loss carryforwards		$ 9.9
Non-US
Tax Credit Carryforward [Line Items]
Number of countries in which entity operates \| country		17

Financial Instruments and Fair Value Measurement - Narrative (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) derivate investment	Dec. 31, 2016 USD ($) investment	Dec. 31, 2015 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments carried at fair value	$ 72,200,000	$ 67,600,000
Purchase of trading securities held-for-investment	2,100,000	1,400,000
Proceeds from the sale of trading securities held-for-investment	$ 300,000	1,600,000
Number of foreign exchange contracts held (foreign_exchange_contract) \| derivate	46
Hedge ineffectiveness with respect to forward exchange cash flow hedges	$ 0	0	$ 0
Long-term debt	987,100,000	990,500,000
Long-term debt, fair value	1,013,200,000	$ 1,017,800,000
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, notional amount	400,000.0
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, notional amount	$ 1,500,000.0
Unobservable inputs for which little or no market data exists (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of available-for-sale securities (investment) \| investment	1	1
Customer Concentration Risk
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Concentration risk, percentage	40.00%

Financial Instruments and Fair Value Measurement - Fair Value Hierarchy (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	$ 126.9	$ 263.5
Available for sale investments	58.4	57.4
Trading securities	13.8	10.2
Deferred compensation plan liabilities	(13.8)	(10.2)
Derivatives:
Forward exchange contracts-Assets	0.2	0.8
Forward exchange contracts-(Liabilities)	(0.7)	(0.1)
Fair value, net asset (liability)	184.8	321.6
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	126.9	263.5
Available for sale investments	0.0	0.0
Trading securities	13.8	10.2
Deferred compensation plan liabilities	(13.8)	(10.2)
Derivatives:
Forward exchange contracts-Assets	0.0	0.0
Forward exchange contracts-(Liabilities)	0.0	0.0
Fair value, net asset (liability)	126.9	263.5
Quoted Prices in Active Markets for Similar Assets (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0.0	0.0
Available for sale investments	54.3	53.6
Trading securities	0.0	0.0
Deferred compensation plan liabilities	0.0	0.0
Derivatives:
Forward exchange contracts-Assets	0.2	0.8
Forward exchange contracts-(Liabilities)	(0.7)	(0.1)
Fair value, net asset (liability)	53.8	54.3
Unobservable inputs for which little or no market data exists (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0.0	0.0
Available for sale investments	4.1	3.8
Trading securities	0.0	0.0
Deferred compensation plan liabilities	0.0	0.0
Derivatives:
Forward exchange contracts-Assets	0.0	0.0
Forward exchange contracts-(Liabilities)	0.0	0.0
Fair value, net asset (liability)	$ 4.1	$ 3.8

Financial Instruments and Fair Value Measurement - Cash Flow Hedging Relationships (Details) - Forward exchange contract - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Gain/(Loss) Recognized in Accumulated Other Comprehensive Loss, net of tax	$ (1.7)	$ (1.4)
Net sales
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain/(Loss) Reclassified into Earnings (Effective Portion), net of tax	(0.3)	(0.3)
Cost of goods sold
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain/(Loss) Reclassified into Earnings (Effective Portion), net of tax	$ (0.6)	$ 0.3

Commitments and Contingencies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Leased Assets [Line Items]
Accrual for environmental loss contingencies	$ 4.9	$ 5.2
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Operating lease rent expense	30.5	$ 28.8	$ 25.7
Due in 2018	18.0
Due in 2019	15.6
Due in 2020	10.8
Due in 2021	8.2
Due in 2022	6.2
Due thereafter	$ 18.8
Maximum
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Operating lease, contract term	11 years

Capital Stock - Common Stock Outstanding (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Common Stock, Shares, Outstanding [Roll Forward]
Common stock, shares outstanding, beginning of period (shares)	55,532,307
Common stock, shares outstanding, end of period (shares)	54,882,154	55,532,307
Class A Common Stock
Common Stock, Shares, Outstanding [Roll Forward]
Common stock, shares outstanding, beginning of period (shares)	0	0	7,167,000
Exercise of stock options/stock appreciation rights (shares)	0	0	0
Director compensation arrangements, net (shares)	0	0	0
Restricted/performance shares activity, net of forfeitures (shares)	0	0	0
Acquisition/surrender of shares (shares)	0	0	0
Share reclassification			(7,167,000)
Common stock, shares outstanding, end of period (shares)	0	0	0
Class B Common Stock
Common Stock, Shares, Outstanding [Roll Forward]
Common stock, shares outstanding, beginning of period (shares)	0	0	51,329,000
Exercise of stock options/stock appreciation rights (shares)	0	0	29,000
Director compensation arrangements, net (shares)	0	0	17,000
Restricted/performance shares activity, net of forfeitures (shares)	0	0	122,000
Acquisition/surrender of shares (shares)	0	0	(708,000)
Share reclassification			(50,789,000)
Common stock, shares outstanding, end of period (shares)	0	0	0
Common Stock
Common Stock, Shares, Outstanding [Roll Forward]
Common stock, shares outstanding, beginning of period (shares)	55,532,000	57,837,000	0
Exercise of stock options/stock appreciation rights (shares)	53,000	78,000	0
Director compensation arrangements, net (shares)	10,000	6,000	0
Restricted/performance shares activity, net of forfeitures (shares)	89,000	98,000	0
Acquisition/surrender of shares (shares)	(802,000)	(2,487,000)	(119,000)
Share reclassification			57,956,000
Common stock, shares outstanding, end of period (shares)	54,882,000	55,532,000	57,837,000

Capital Stock - Narrative (Details)		12 Months Ended
Capital Stock - Narrative (Details)	Dec. 23, 2015 vote / shares vote $ / shares	Dec. 22, 2015 vote / shares $ / shares shares	Dec. 31, 2017 $ / shares shares	Dec. 31, 2016 $ / shares shares	Dec. 31, 2015 shares	Dec. 31, 2014 shares
Class of Stock [Line Items]
Common stock, shares, outstanding (shares)			54,882,154	55,532,307
Common stock, par value (USD per share) \| $ / shares			$ 0.01	$ 0.01
Voting rights, percentage		36.00%
Class A Common Stock
Class of Stock [Line Items]
Common stock, shares, outstanding (shares)			0	0	0	7,167,000
Reclassification of stock, proposed premium per share (USD per share) \| $ / shares	$ 28.00
Common stock, voting rights (votes per share) \| vote / shares		20
Class B Common Stock
Class of Stock [Line Items]
Common stock, shares, outstanding (shares)			0	0	0	51,329,000
Common stock, par value (USD per share) \| $ / shares	$ 0.01
Common stock, voting rights (votes per share) \| vote / shares		1
Common Stock
Class of Stock [Line Items]
Common stock, shares, outstanding (shares)			54,882,000	55,532,000	57,837,000	0
Reclassification of stock, voting rights of proposed share class (vote) \| vote	1
Common stock, voting rights (votes per share) \| vote / shares	1
Louie E. Roche Trust and Harvey Hubbell Trust \| Class A Common Stock
Class of Stock [Line Items]
Common stock, shares, outstanding (shares)		3,488,460
Common stock, par value (USD per share) \| $ / shares		$ 0.01
Ownership percentage, by shareholder		49.00%

Capital Stock - Reserved Common Stock (Details) - Common Stock shares in Thousands	Dec. 31, 2017 shares
Class of Stock [Line Items]
Future grant of stock-based compensation	2,609
Shares reserved under other equity compensation plans	161
TOTAL	2,770

Stock-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	Feb. 15, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Feb. 28, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of additional shares authorized (shares)				2,800,000.0
Maximum number of shares authorized (shares)				9,700,000.0
Pre-tax stock-based compensation cost		$ 22.3	$ 22.3	$ 17.0
Income tax benefits		5.4	8.2	6.2
Net tax windfall as a result of exercise or vesting of awards		2.5	3.7	0.9
Unrecognized compensation cost related to non-vested awards		31.1
Capitalized to inventory		$ 0.3	$ 0.2	$ 0.2
Shares issued to non-employee directors (shares)		8,480	9,128	8,008
Weighted average fair value (USD per share)		$ 118.55	$ 105.48	$ 97.48	$ 106.44
Restricted Stock Units RSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage		33.33%	33.33%	33.33%
Weighted average fair value (USD per share)		$ 123.39	$ 109.95	$ 96.26
Vested in period total fair value		$ 6.6	$ 6.4	$ 7.7
Shares granted (shares)		81,000
Shares vested (shares)		62,000
Restricted Stock Awards, Market Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award performance period		3 years
Award vesting percentage		100.00%
Vested in period total fair value		$ 3.1
Shares vested (shares)		23,280
Stock Appreciation Rights SARS
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value (USD per share)		$ 127.28
Award vesting period		3 years
Award, expiration period		10 years
SARS exercised intrinsic value		$ 10.1	$ 13.8	$ 4.8
Shares granted (shares)		432,000
Performance Shares - Market Condition
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award performance period		3 years
Weighted average fair value (USD per share)		$ 142.89	$ 126.65	$ 105.77
Shares granted (shares)		24,675	29,012	32,687
Performance Shares - Market Condition \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance based criteria plan payout percentage, market condition		0.00%
Performance Shares - Market Condition \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance based criteria plan payout percentage, market condition		200.00%
Performance Shares - Market Condition \| Subsequent Event \| December 2014 Grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested in period total fair value	$ 2.0
Shares vested (shares)	15,141
Market based criteria, actual payout percentage						64.00%
Performance Shares - Performance Condition
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award performance period		3 years
Shares granted (shares)		24,675	29,012	32,687
Performance share payout at target		100.00%
Performance Shares - Performance Condition \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance based criteria plan payout percentage		0.00%
Performance Shares - Performance Condition \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance based criteria plan payout percentage		250.00%
Selling and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax stock-based compensation cost		$ 21.1	$ 21.6	$ 16.2
Cost of goods sold
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax stock-based compensation cost		$ 1.2	$ 0.7	$ 0.8

Stock-Based Compensation - Valuation Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Price on Measurement Date (USD per share)	$ 127.51	$ 113.69	$ 97.48
Expected Volatility	24.70%	25.60%	23.30%
Risk Free Interest Rate	1.90%	1.40%	1.30%
Expected Term	3 years	3 years	3 years
Weighted Avg. Grant Date Fair Value	$ 119.88	$ 104.93	$ 87.61

Stock-Based Compensation - Restricted Stock Option Activity (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Weighted Average Exercise Price (USD per share)
OUTSTANDING AT DECEMBER 31, 2016 (USD per share)	$ 104.93	$ 87.61
Weighted average fair value (USD per share)	118.55	105.48	$ 97.48	$ 106.44
OUTSTANDING AT DECEMBER 31, 2017 (USD per Share)	$ 119.88	$ 104.93	87.61
Restricted Stock Units RSU
Number of Shares
OUTSTANDING AT DECEMBER 31, 2016 (shares)	224
Shares granted (shares)	81
Shares vested (shares)	(62)
Shares forfeited (shares)	(4)
OUTSTANDING AT DECEMBER 31, 2017 (shares)	239	224
Weighted Average Exercise Price (USD per share)
OUTSTANDING AT DECEMBER 31, 2016 (USD per share)	$ 102.37
Weighted average fair value (USD per share)	123.39	$ 109.95	$ 96.26
Shares vested (USD per share)	106.06
Forfeited (USD per share)	104.54
OUTSTANDING AT DECEMBER 31, 2017 (USD per Share)	$ 108.51	$ 102.37

Stock-Based Compensation - Stock Appreciation RIghts (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Weighted Average Exercise Price (USD per share)
OUTSTANDING AT DECEMBER 31, 2016 (USD per share)	$ 104.93	$ 87.61
Weighted average fair value (USD per share)	118.55	105.48	$ 97.48	$ 106.44
OUTSTANDING AT DECEMBER 31, 2017 (USD per Share)	$ 119.88	$ 104.93	$ 87.61
Stock Appreciation Rights SARS
Number of Rights
OUTSTANDING AT DECEMBER 31, 2016 (shares)	1,811
Shares granted (shares)	432
Exercised (shares)	(191)
Shares forfeited (shares)	(9)
Canceled (shares)	(1)
OUTSTANDING AT DECEMBER 31, 2017 (shares)	2,042	1,811
EXERCISABLE AT DECEMBER 31, 2016 (shares)	1,241
Weighted Average Exercise Price (USD per share)
OUTSTANDING AT DECEMBER 31, 2016 (USD per share)	$ 94.51
Weighted average fair value (USD per share)	127.28
Exercised (USD per share)	70.78
Forfeited (USD per share)	107.39
Canceled (USD per share)	97.48
OUTSTANDING AT DECEMBER 31, 2017 (USD per Share)	103.59	$ 94.51
Options, exercisable, weighted average exercise price (USD per share)	$ 93.89
Weighted average remaining contractual term, outstanding share	7 years 4 months 24 days
Weighted average remaining contractual term, exercisable	6 years 2 months 12 days
Aggregate intrinsic value, outstanding	$ 64,841
Aggregate intrinsic value, exercisable	$ 51,420

Stock-Based Compensation - Fair Value Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Price on Measurement Date (USD per share)	$ 127.51	$ 113.69	$ 97.48
Expected Volatility	24.70%	25.60%	23.30%
Risk Free Interest Rate	1.90%	1.40%	1.30%
Expected Term	3 years	3 years	3 years
Weighted average fair value (USD per share)	$ 118.55	$ 105.48	$ 97.48	$ 106.44
Stock Appreciation Rights SARS
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected Dividend Yield	2.60%	2.60%	2.70%
Expected Volatility	18.00%	22.30%	22.70%
Risk Free Interest Rate	2.20%	1.90%	1.70%
Expected Term	5 years 6 months	5 years 6 months	5 years 6 months
Weighted Avg. Grant Date Fair Value of 1 SAR (USD per share)	$ 17.45	$ 18.76	$ 16.05
Weighted average fair value (USD per share)	127.28
Performance Shares - Market Condition
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Price on Measurement Date (USD per share)	$ 127.51	$ 113.69	$ 97.48
Expected Dividend Yield	2.40%	2.50%	2.60%
Expected Volatility	24.70%	25.60%	23.30%
Risk Free Interest Rate	1.90%	1.40%	1.30%
Expected Term	3 years	3 years	3 years
Weighted average fair value (USD per share)	$ 142.89	$ 126.65	$ 105.77

Stock-Based Compensation - Performance Shares Granted During the Period (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value (USD per share)	$ 118.55	$ 105.48	$ 97.48	$ 106.44
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding (shares)	24,675	28,524	31,024	23,688
Minimum \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance based criteria plan payout percentage	0.00%	0.00%	0.00%	0.00%
Maximum \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance based criteria plan payout percentage	250.00%	250.00%	250.00%	250.00%

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net Income attributable to Hubbell	$ 20.4	$ 80.8	$ 79.1	$ 62.8	$ 64.4	$ 86.7	$ 81.0	$ 60.9	$ 243.1	$ 293.0	$ 277.3
Less: Earnings allocated to participating securities									(0.8)	(0.9)	(0.7)
Net income available to common shareholders									$ 242.3	$ 292.1	$ 276.6
Average number of common shares outstanding									54.8	55.5	57.7
Potential dilutive shares									0.3	0.2	0.3
Average number of diluted shares outstanding (shares)									55.1	55.7	58.0
Basic (USD per share)	$ 0.37	$ 1.47	$ 1.44	$ 1.13	$ 1.16	$ 1.56	$ 1.46	$ 1.08	$ 4.42	$ 5.26	$ 4.79
Diluted (USD per share)	$ 0.37	$ 1.47	$ 1.43	$ 1.13	$ 1.16	$ 1.56	$ 1.45	$ 1.08	$ 4.39	$ 5.24	$ 4.77

Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period	$ 1,603.2
Other comprehensive income (loss)	32.7	$ (78.3)	$ (59.9)
End of period	1,647.9	1,603.2
Cash Flow Hedge (Loss) Gain
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period	0.0	1.4	0.0
Other comprehensive income (loss) before Reclassifications	(1.7)	(1.4)	1.7
Amounts reclassified from accumulated other comprehensive loss	0.9	0.0	(0.3)
Other comprehensive income (loss)	(0.8)	(1.4)	1.4
End of period	(0.8)	0.0	1.4
Unrealized Gain (Loss) on Available-for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period	(1.2)	0.0	0.3
Other comprehensive income (loss) before Reclassifications	0.6	(1.2)	(0.3)
Amounts reclassified from accumulated other comprehensive loss	0.0	0.0	0.0
Other comprehensive income (loss)	0.6	(1.2)	(0.3)
End of period	(0.6)	(1.2)	0.0
Pension and Post Retirement Benefit Plan Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period	(180.5)	(140.2)	(124.7)
Other comprehensive income (loss) before Reclassifications	(3.4)	(48.5)	(22.5)
Amounts reclassified from accumulated other comprehensive loss	7.4	8.2	7.0
Other comprehensive income (loss)	4.0	(40.3)	(15.5)
End of period	(176.5)	(180.5)	(140.2)
Cumulative Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period	(120.8)	(85.4)	(39.9)
Other comprehensive income (loss) before Reclassifications	28.9	(35.4)	(45.5)
Amounts reclassified from accumulated other comprehensive loss	0.0	0.0	0.0
Other comprehensive income (loss)	28.9	(35.4)	(45.5)
End of period	(91.9)	(120.8)	(85.4)
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period	(302.5)	(224.2)	(164.3)
Other comprehensive income (loss) before Reclassifications	24.4	(86.5)	(66.6)
Amounts reclassified from accumulated other comprehensive loss	8.3	8.2	6.7
Other comprehensive income (loss)	32.7	(78.3)	(59.9)
End of period	$ (269.8)	$ (302.5)	$ (224.2)

Accumulated Other Comprehensive Loss - Reclassifications Out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net sales	$ 917.7	$ 950.5	$ 948.3	$ 852.3	$ 854.2	$ 907.4	$ 908.8	$ 834.8	$ 3,668.8	$ 3,505.2	$ 3,390.4
Cost of goods sold	$ 629.2	$ 643.6	$ 653.6	$ 590.5	$ 595.6	$ 618.7	$ 615.3	$ 574.9	2,516.9	2,404.5	2,298.6
Total before tax									443.1	430.4	418.6
Tax (expense) benefit									(193.2)	(132.6)	(136.5)
Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
(Loss) gain net of tax									(8.3)	(8.2)	(6.7)
Cash Flow Hedge (Loss) Gain
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
(Loss) gain net of tax									(0.9)	0.0	0.3
Pension and Post Retirement Benefit Plan Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from accumulated other comprehensive income, before tax									(10.9)	(13.0)
Tax benefit (expense)									3.5	4.8
(Loss) gain net of tax									(7.4)	(8.2)	$ (7.0)
Prior-service costs
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from accumulated other comprehensive income, before tax									0.9	0.9
Actuarial gains/(losses)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from accumulated other comprehensive income, before tax									(11.4)	(13.9)
Settlement and curtailment losses
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from accumulated other comprehensive income, before tax									(0.4)	0.0
Forward Contracts \| Cash Flow Hedge (Loss) Gain \| Reclassification out of accumulated other comprehensive income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net sales									(0.4)	(0.3)
Cost of goods sold									(0.9)	0.3
Total before tax									(1.3)	0.0
Tax (expense) benefit									0.4	0.0
Gain (loss) net of tax									$ (0.9)	$ 0.0

- Industry Segments Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Sales:
Net sales	$ 917.7	$ 950.5	$ 948.3	$ 852.3	$ 854.2	$ 907.4	$ 908.8	$ 834.8	$ 3,668.8	$ 3,505.2	$ 3,390.4
Operating Income:
Operating Income									503.7	477.8	474.6
Interest expense									(44.9)	(43.4)	(31.0)
Loss on extinguishment of debt									(10.1)	0.0	0.0
Income before income taxes									443.1	430.4	418.6
Assets:
Assets	3,720.6				3,525.0				3,720.6	3,525.0	3,208.7
Capital Expenditures:
Capital expenditures									79.7	67.2	77.1
Depreciation and Amortization:
Depreciation and amortization									99.8	92.3	85.2
Electrical
Net Sales:
Net sales									2,532.8	2,460.2	2,388.3
Operating Income:
Operating Income									282.5	267.4	279.0
Power
Net Sales:
Net sales									1,136.0	1,045.0	1,002.1
Operating Income:
Operating Income									221.2	210.4	195.6
Operating Segments \| Electrical
Assets:
Assets	2,344.7				2,246.0				2,344.7	2,246.0	2,120.9
Capital Expenditures:
Capital expenditures									48.0	43.4	47.9
Depreciation and Amortization:
Depreciation and amortization									65.7	61.2	56.2
Operating Segments \| Power
Assets:
Assets	1,102.2				911.5				1,102.2	911.5	839.7
Capital Expenditures:
Capital expenditures									29.0	22.7	28.4
Depreciation and Amortization:
Depreciation and amortization									34.1	31.1	29.0
Segment Reconciling Items
Operating Income:
Interest expense									(44.9)	(43.4)	(31.0)
Investment income and other expense, net									(5.6)	(4.0)	(25.0)
General Corporate
Assets:
Assets	$ 273.7				$ 367.5				273.7	367.5	248.1
Capital Expenditures:
Capital expenditures									$ 2.7	$ 1.1	$ 0.8

- Product Class Data (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
- Product Class Data (Details) - USD ($) $ in Millions	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Sales:
Net sales	$ 917.7	$ 950.5	$ 948.3	$ 852.3	$ 854.2	$ 907.4	$ 908.8	$ 834.8	$ 3,668.8	$ 3,505.2	$ 3,390.4
Electrical Systems
Net Sales:
Net sales									1,597.1	1,514.4	1,476.7
Lighting
Net Sales:
Net sales									935.7	945.8	911.6
Power
Net Sales:
Net sales									$ 1,136.0	$ 1,045.0	$ 1,002.1

Industry Segments and Geographic Area Information - Geographic Area (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Sales:
Net sales	$ 917.7	$ 950.5	$ 948.3	$ 852.3	$ 854.2	$ 907.4	$ 908.8	$ 834.8	$ 3,668.8	$ 3,505.2	$ 3,390.4
Operating Income:
Operating Income									503.7	477.8	474.6
Long-lived Assets:
Long-Lived Assets	2,110.2				1,963.0				2,110.2	1,963.0	1,814.8
United States
Net Sales:
Net sales									3,280.9	3,147.4	3,008.4
Operating Income:
Operating Income									422.1	419.1	426.1
Long-lived Assets:
Long-Lived Assets	1,877.4				1,762.9				1,877.4	1,762.9	1,627.7
International
Net Sales:
Net sales									387.9	357.8	382.0
Operating Income:
Operating Income									81.6	58.7	48.5
Long-lived Assets:
Long-Lived Assets	$ 232.8				$ 200.1				$ 232.8	$ 200.1	$ 187.1

Industry Segments and Geographic Area Information - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) group	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Concentration Risk [Line Items]
Export sales from United States \| $	$ 217.2	$ 213.8	$ 224.9
Net Sales Total \| Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	11.00%	10.00%	11.00%
Long-lived assets Total \| Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	11.00%	10.00%	10.00%
Canada \| Net Sales Total \| Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	31.00%
Canada \| Long-lived assets Total \| Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	16.00%
United Kingdom \| Net Sales Total \| Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	21.00%
United Kingdom \| Long-lived assets Total \| Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	31.00%
BRAZIL \| Net Sales Total \| Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	12.00%
MEXICO \| Long-lived assets Total \| Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	19.00%
Electrical
Concentration Risk [Line Items]
Number Of business groups \| group	3

Guarantees (Details) - USD ($) $ in Millions	12 Months Ended
Guarantees (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Movement in Standard Product Warranty Accrual [Roll Forward]
Beginning balance	$ 13.8	$ 13.2
Provision	10.0	9.7
Expenditures/other	(9.8)	(9.1)
Ending balance	$ 14.0	$ 13.8

Restructuring Costs - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Pre-tax restructuring costs		$ 20.3	$ 35.0	$ 23.6
Accrued liability settlement term		19 years
Withdrawal from Multiemployer Defined Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Pre-tax restructuring costs	$ 12.5
2016 Restructuring Actions
Defined Benefit Plan Disclosure [Line Items]
Pre-tax restructuring costs		$ 6.3
2016 Restructuring Actions \| Withdrawal from Multiemployer Defined Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Pre-tax restructuring costs	12.5		12.5
Electrical
Defined Benefit Plan Disclosure [Line Items]
Pre-tax restructuring costs		$ 16.9	$ 33.9	$ 21.7
Electrical \| 2016 Restructuring Actions \| Withdrawal from Multiemployer Defined Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Pre-tax restructuring costs	$ 12.5

Restructuring Costs - By Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring costs	$ 20.3	$ 35.0	$ 23.6
Cost of goods sold
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring costs	13.7	27.5	15.3
Selling & administrative expense
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring costs	6.6	7.5	8.3
Electrical
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring costs	16.9	33.9	21.7
Electrical \| Cost of goods sold
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring costs	11.5	27.3	14.5
Electrical \| Selling & administrative expense
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring costs	5.4	6.6	7.2
Power
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring costs	3.4	1.1	1.9
Power \| Cost of goods sold
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring costs	2.2	0.2	0.8
Power \| Selling & administrative expense
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring costs	$ 1.2	$ 0.9	$ 1.1

Restructuring Costs - Reserve (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Reserve [Roll Forward]
Beginning accrued restructuring balance 1/1/16		$ 24.5
Pre-tax restructuring costs		20.3	$ 35.0	$ 23.6
Utilization and foreign exchange		(23.9)
Ending accrued restructuring balance 12/31/2016	$ 24.5	20.9	24.5
2017 Restructuring Actions
Restructuring Reserve [Roll Forward]
Beginning accrued restructuring balance 1/1/16		0.0
Pre-tax restructuring costs		14.0
Utilization and foreign exchange		(8.6)
Ending accrued restructuring balance 12/31/2016	0.0	5.4	0.0
2016 Restructuring Actions
Restructuring Reserve [Roll Forward]
Beginning accrued restructuring balance 1/1/16		24.5
Pre-tax restructuring costs		6.3
Utilization and foreign exchange		(15.3)
Ending accrued restructuring balance 12/31/2016	24.5	15.5	24.5
Severance \| 2017 Restructuring Actions
Restructuring Reserve [Roll Forward]
Beginning accrued restructuring balance 1/1/16		0.0
Pre-tax restructuring costs		7.4
Utilization and foreign exchange		(3.8)
Ending accrued restructuring balance 12/31/2016	0.0	3.6	0.0
Severance \| 2016 Restructuring Actions
Restructuring Reserve [Roll Forward]
Beginning accrued restructuring balance 1/1/16		10.4
Pre-tax restructuring costs		(2.2)
Utilization and foreign exchange		(6.4)
Ending accrued restructuring balance 12/31/2016	10.4	1.8	10.4
Asset write-downs \| 2017 Restructuring Actions
Restructuring Reserve [Roll Forward]
Beginning accrued restructuring balance 1/1/16		0.0
Pre-tax restructuring costs		0.5
Utilization and foreign exchange		(0.5)
Ending accrued restructuring balance 12/31/2016	0.0	0.0	0.0
Asset write-downs \| 2016 Restructuring Actions
Restructuring Reserve [Roll Forward]
Beginning accrued restructuring balance 1/1/16		0.0
Pre-tax restructuring costs		0.0
Utilization and foreign exchange		0.0
Ending accrued restructuring balance 12/31/2016	0.0	0.0	0.0
Facility closure and other costs \| 2017 Restructuring Actions
Restructuring Reserve [Roll Forward]
Beginning accrued restructuring balance 1/1/16		0.0
Pre-tax restructuring costs		6.1
Utilization and foreign exchange		(4.3)
Ending accrued restructuring balance 12/31/2016	0.0	1.8	0.0
Facility closure and other costs \| 2016 Restructuring Actions
Restructuring Reserve [Roll Forward]
Beginning accrued restructuring balance 1/1/16		14.1
Pre-tax restructuring costs		8.5
Utilization and foreign exchange		(8.9)
Ending accrued restructuring balance 12/31/2016	14.1	$ 13.7	14.1
Withdrawal from Multiemployer Defined Benefit Plan
Restructuring Reserve [Roll Forward]
Pre-tax restructuring costs	12.5
Withdrawal from Multiemployer Defined Benefit Plan \| 2016 Restructuring Actions
Restructuring Reserve [Roll Forward]
Pre-tax restructuring costs	$ 12.5		$ 12.5

Restructuring Costs - Summary of Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Expected Costs	$ 78.5
Cost incurred to date	20.3	$ 35.0	$ 19.2
Remaining costs at 12/31/17	4.0
2017 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	16.9
Cost incurred to date	14.0	0.0
Remaining costs at 12/31/17	2.9
2016 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	36.7
Cost incurred to date	3.8	31.8
Remaining costs at 12/31/17	1.1
2015 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	24.9
Cost incurred to date	2.5	3.2	19.2
Remaining costs at 12/31/17	0.0
Electrical \| 2017 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	13.0
Cost incurred to date	10.6	0.0
Remaining costs at 12/31/17	2.4
Electrical \| 2016 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	35.4
Cost incurred to date	3.8	30.7
Remaining costs at 12/31/17	0.9
Electrical \| 2015 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	23.0
Cost incurred to date	2.5	3.2	17.3
Remaining costs at 12/31/17	0.0
Power \| 2017 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	3.9
Cost incurred to date	3.4	0.0
Remaining costs at 12/31/17	0.5
Power \| 2016 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	1.3
Cost incurred to date	0.0	$ 1.1
Remaining costs at 12/31/17	0.2
Power \| 2015 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	$ 1.9
Cost incurred to date			$ 1.9

Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 917.7	$ 950.5	$ 948.3	$ 852.3	$ 854.2	$ 907.4	$ 908.8	$ 834.8	$ 3,668.8	$ 3,505.2	$ 3,390.4
Cost of goods sold	629.2	643.6	653.6	590.5	595.6	618.7	615.3	574.9	2,516.9	2,404.5	2,298.6
Gross profit	288.5	306.9	294.7	261.8	258.6	288.7	293.5	259.9	1,151.9	1,100.7	1,091.8
Selling & administrative expenses	165.8	160.5	164.1	157.7	150.8	152.7	161.4	158.0	648.2	622.9	617.2
Net income	22.4	82.8	80.8	63.9	65.7	88.1	82.0	62.0	249.9	297.8	282.1
Net Income attributable to Hubbell	$ 20.4	$ 80.8	$ 79.1	$ 62.8	$ 64.4	$ 86.7	$ 81.0	$ 60.9	$ 243.1	$ 293.0	$ 277.3
Earning Per Share - Basic (USD per share)	$ 0.37	$ 1.47	$ 1.44	$ 1.13	$ 1.16	$ 1.56	$ 1.46	$ 1.08	$ 4.42	$ 5.26	$ 4.79
Earning Per Share - Diluted (USD per share)	$ 0.37	$ 1.47	$ 1.43	$ 1.13	$ 1.16	$ 1.56	$ 1.45	$ 1.08	$ 4.39	$ 5.24	$ 4.77

Subsequent Events (Details) - Subsequent Event - USD ($)		1 Months Ended
	Feb. 02, 2018	Feb. 15, 2018	Jan. 31, 2018
Notes 2028 Term \| Senior Notes
Subsequent Event [Line Items]
Face amount	$ 450,000,000
Term Loan Agreement \| Line of Credit
Subsequent Event [Line Items]
Line of credit, maximum borrowing capacity	500,000,000		$ 500,000,000
Aclara
Subsequent Event [Line Items]
Consideration transferred to acquire business	$ 1,100,000,000	$ 1,100,000,000

Valuation and Qualifying Accounts and Reserves (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowances for doubtful accounts receivable:
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 4.7	$ 4.7	$ 3.4
Additions / (Reversals) Charged to Costs and Expenses	1.5	0.8	2.7
Deductions	(3.5)	(0.8)	(1.4)
Acquisitions	1.9	0.0	0.0
Balance at End of Year	4.6	4.7	4.7
Allowance for credit memos, returns and cash discounts:
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	45.9	41.5	36.7
Additions / (Reversals) Charged to Costs and Expenses	260.8	249.2	233.2
Deductions	(256.3)	(244.8)	(228.4)
Acquisitions	0.1	0.0	0.0
Balance at End of Year	50.5	45.9	41.5
Valuation allowance on deferred tax assets:
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	22.6	22.0	34.3
Additions / (Reversals) Charged to Costs and Expenses	(3.2)	0.6	(12.3)
Deductions	0.0	0.0	0.0
Acquisitions	0.0	0.0	0.0
Balance at End of Year	$ 19.4	$ 22.6	$ 22.0

Consolidated Statement of Changes in Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Common stock, dividends declared (USD per share)	$ 2.87	$ 2.59	$ 2.31