Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2018	Apr. 23, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Amendment Flag	false
Entity Registrant Name	HUBBELL INCORPORATED
Entity Central Index Key	0000048898
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock Shares Outstanding		54,863,572
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1

Condensed Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Net sales	$ 991.2	$ 852.3
Cost of goods sold	708.3	589.7
Gross profit	282.9	262.6
Selling & administrative expenses	183.3	154.8
Operating income	99.6	107.8
Interest expense, net	(17.3)	(11.1)
Other (expense) income, net	(6.5)	(5.8)
Total other expense	(23.8)	(16.9)
Income before income taxes	75.8	90.9
Provision for income taxes	16.0	27.0
Net income	59.8	63.9
Less: Net income attributable to noncontrolling interest	1.5	1.1
Net income	$ 58.3	$ 62.8
Earnings per share
Basic (USD per share)	$ 1.06	$ 1.13
Diluted (USD per share)	1.05	1.13
Cash dividends per common share (USD per share)	$ 0.77	$ 0.7

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 59.8	$ 63.9
Other comprehensive income (loss):
Foreign currency translation adjustments	9.8	11.5
Pension and post retirement benefit plans’ prior service costs and net actuarial gains, net of taxes	2.0	1.7
Unrealized gain (loss) on investments, net of taxes	(0.3)	0.4
Unrealized gain (loss) on cash flow hedges, net of taxes	0.6	(0.1)
Other comprehensive income	12.1	13.5
Total comprehensive income	71.9	77.4
Less: Comprehensive income attributable to noncontrolling interest	1.5	1.1
Comprehensive income attributable to Hubbell	$ 70.4	$ 76.3

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Pension and post-retirement benefit plans’ prior service costs and net actuarial gains, net of taxes	$ (0.6)	$ (0.9)
Unrealized gain or (loss) on investment, net of taxes	0.0	(0.4)
Unrealized gain (loss) on cash flow hedges, net of taxes	$ (0.2)	$ 0.1

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 216.3	$ 375.0
Short-term investments	15.5	14.5
Accounts receivable, net	704.0	540.3
Inventories, net	714.3	634.7
Other current assets	70.7	39.6
Total Current Assets	1,720.8	1,604.1
Property, Plant, and Equipment, net	494.9	458.3
Other Assets
Investments	56.5	57.7
Goodwill	1,760.1	1,089.0
Intangible assets, net	889.5	460.4
Other long-term assets	53.6	51.1
TOTAL ASSETS	4,975.4	3,720.6
Current Liabilities
Short-term debt and current portion of long-term debt	177.5	68.1
Accounts payable	374.5	326.5
Accrued salaries, wages and employee benefits	71.0	76.6
Accrued insurance	64.6	60.0
Other accrued liabilities	210.9	174.9
Total Current Liabilities	898.5	706.1
Long-Term Debt	1,903.2	987.1
Other Non-Current Liabilities	495.2	379.5
TOTAL LIABILITIES	3,296.9	2,072.7
Total Hubbell Shareholders’ Equity	1,662.0	1,634.2
Noncontrolling interest	16.5	13.7
Total Equity	1,678.5	1,647.9
TOTAL LIABILITIES AND EQUITY	$ 4,975.4	$ 3,720.6

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash Flows from Operating Activities
Net income	$ 59.8	$ 63.9
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	40.0	24.2
Deferred income taxes	(1.4)	0.7
Stock-based compensation	5.1	4.2
Changes in assets and liabilities, excluding effects of acquisitions:
Increase in accounts receivable, net	(46.9)	(13.1)
Increase in inventories, net	(19.1)	(12.2)
(Decrease) increase in accounts payable	(0.7)	8.5
Decrease in current liabilities	(35.7)	(18.3)
Changes in other assets and liabilities, net	(0.5)	8.3
Contribution to qualified defined benefit pension plans	(0.5)	(0.4)
Other, net	(0.5)	(2.9)
Net cash (used) provided by operating activities	(0.4)	62.9
Cash Flows from Investing Activities
Capital expenditures	(22.0)	(13.6)
Acquisition of businesses, net of cash acquired	(1,119.4)	(19.2)
Purchases of available-for-sale investments	(5.0)	(3.3)
Proceeds from available-for-sale investments	5.7	2.4
Other, net	0.9	0.9
Net cash used in investing activities	(1,139.8)	(32.8)
Cash Flows from Financing Activities
Long-term debt borrowings	947.5	0.0
Short-term debt borrowings, net	84.5	2.0
Payment of dividends	(42.2)	(38.8)
Payment of dividends to noncontrolling interest	(1.1)	(1.4)
Repurchase of common shares	0.0	(52.6)
Debt issuance costs	(7.6)	0.0
Other, net	(6.1)	(3.3)
Net cash (used) provided by financing activities	975.0	(94.1)
Effect of foreign currency exchange rate changes on cash and cash equivalents	6.5	7.4
Decrease in cash and cash equivalents	(158.7)	(56.6)
Cash and cash equivalents
Beginning of period	375.0	437.6
End of period	$ 216.3	$ 381.0

Basis of Presentation

3 Months Ended

Mar. 31, 2018

Accounting Policies [Abstract]

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements of Hubbell Incorporated (“Hubbell”, the “Company”, “registrant”, “we”, “our” or “us”, which references include its divisions and subsidiaries) have been prepared in accordance with generally accepted accounting principles (“GAAP”) for interim financial information. Accordingly, they do not include all of the information and footnotes required by United States of America (“U.S.”) GAAP for audited financial statements. In the opinion of management, all adjustments consisting only of normal recurring adjustments considered necessary for a fair statement of the results of the periods presented have been included. Operating results for the three months ended March 31, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018.

The balance sheet at December 31, 2017 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the U.S. for complete financial statements.

For further information, refer to the consolidated financial statements and footnotes thereto included in the Hubbell Incorporated Annual Report on Form 10-K for the year ended December 31, 2017.

On February 2, 2018 the Company acquired Meter Readings Holding Group, LLC ("Aclara Technologies" or "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 has been added to the Power segment and is intended to extend the Power segment's capabilities into smart automation technologies, accelerate ongoing innovation efforts to address utility customer demand for data and integrated solutions, and expand the segment's reach to a broader set of utility customers. The results of operations of Aclara are included in Hubbell's results beginning on February 2, 2018.

Recent Accounting Pronouncements

In February 2018, the Financial Accounting Standards Board (“FASB”) issued an Accounting Standards Update (ASU 2018-02) relating to the reclassification of certain tax effects from accumulated other comprehensive income/(loss). The new guidance allows an entity to reclassify the income tax effects of the Public Law 115-97 "An Act to Provide Reconciliation Pursuant to Titles II and V of the Concurrent Resolution on the Budget for Fiscal Year 2018", commonly known as the Tax Cuts and Job Act of 2017 ("TCJA") on items within accumulated other comprehensive income/(loss) to retained earnings. This new guidance is effective for fiscal years beginning after December 15, 2018, with early adoption permitted. The new standard must be adopted retrospectively to each period in which the effect of the change in the U.S. federal corporate income tax rate in the TCJA is recognized. The Company is currently assessing the impact of adopting this standard on its financial statements.

In response to the enactment of the TCJA, the Securities and Exchange Commission’s Office of the Chief Accountant published Staff Accounting Bulletin 118 ("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 TCJA 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, Income Taxes, (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 the fourth quarter of 2017, we recognized a provisional tax amount of approximately $57 million as a component of income tax expense from continuing operations for certain one-time items related to the TCJA for which we were able to determine a reasonable estimate. During the first quarter of 2018, the Company did not record any material adjustment to the provisional amounts recorded in the fourth quarter of 2017 or include a provisional amount for the income tax effects of any further repatriation of our unremitted foreign earnings as we continue to obtain, prepare, and analyze information and evaluate legislative and authoritative guidance being issued.

In March 2017, the FASB issued an Accounting Standards Update (ASU 2017-07) relating to the presentation of net periodic pension costs and net periodic post-retirement benefit cost. The new guidance requires the service 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 components to be reported outside of operating income. The Company adopted the requirements of the new standard in the first quarter of 2018 and applied the guidance on a retrospective basis, as required by the standard. The impact to our fiscal quarters and year-ended 2017 is shown in the table below (in millions):



	Three Months Ended												Twelve Months Ended
(in millions, except per share amounts)	Dec 31, 2017			Sep 30, 2017			Jun 30, 2017			Mar 31, 2017			Dec 31, 2017
Cost of goods sold	$	(0.9	)	$	(0.8	)	$	(0.8	)	$	(0.8	)	$	(3.3	)
Selling & administrative expenses	(2.9		)	(3.0		)	(3.0		)	(2.9		)	(11.8		)
Total operating expenses	(3.8		)	(3.8		)	(3.8		)	(3.7		)	(15.1		)
Operating income	3.8			3.8			3.8			3.7			15.1
Total other expense	(3.8		)	(3.8		)	(3.8		)	(3.7		)	(15.1		)
Net income	$	—		$	—		$	—		$	—		$	—

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 Company will adopt the standard as of January 1, 2019. 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 our results of operations.

In May 2014, the FASB issued an Accounting Standards Update (ASU 2014-09) related to new revenue recognition guidance (ASC 606) 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.

Effective January 1, 2018, the Company adopted the requirements of ASC 606 using the modified retrospective approach. The Company applied the guidance to all contracts and recognized a cumulative effect adjustment to Retained Earnings as of January, 1, 2018 of $0.6 million. The impacts to the financial statements are primarily related to balance sheet classification, including amounts associated with the change in balance sheet classification of the sales returns reserves, while the impacts on the income statement reflect the change in classification of restocking fees. The impact to our financial statements for the quarter ended March 31, 2018 was as follows (in millions):



	For the Period Ended March 31, 2018
Income Statement	As Reported		Balances Without Adoption of ASC 606		Effect of Adoption Higher/(Lower)
Net sales	$	991.2	$	990.4	$	0.8

Costs and expenses
Cost of goods sold	$	708.3	$	707.5	$	0.8



	For the Period Ended March 31, 2018
Balance Sheet	As Reported		Balances Without Adoption of ASC 606		Effect of Adoption Higher/(Lower)
ASSETS
Accounts receivable, net	$	704.0	$	685.5	$	(18.5	)
Inventories, net	714.3		725.8		11.5
Other current assets	70.7		59.9		(10.8		)
Total Assets	$	4,975.4	$	4,957.6	$	(17.8	)

LIABILITIES
Other accrued liabilities	$	210.9	$	193.7	$	(17.2	)
Total Liabilities	$	3,296.9	$	3,279.7	$	(17.2	)

EQUITY
Retained Earnings	$	1,908.9	$	1,908.3	$	(0.6	)
Total Equity	$	1,678.5	$	1,677.9	$	(0.6	)

Revenue

3 Months Ended

Mar. 31, 2018

Revenue from Contract with Customer [Abstract]

Revenue

The Company recognizes revenue when performance obligations identified under the terms of contracts with its customers are satisfied, which generally occurs, for products, upon the transfer of control in accordance with the contractual terms and conditions of the sale. The majority of the Company’s revenue associated with products is recognized at a point in time when the product is shipped to the customer, with a relatively small amount of transactions in the Power segment recognized upon delivery of the product at the destination. Revenue from service contracts and post-shipment performance obligations are less than three percent of total annual consolidated net revenue and those service contracts and post-shipment obligations are primarily within the Power segment. Revenue from service contracts and post-shipment performance obligations is recognized when or as those obligations are satisfied. The Company primarily offers assurance-type standard warranties that do not represent separate performance obligations and on occasion will separately offer and price extended warranties that are separate performance obligations for which the associated revenue is recognized over-time based on the extended warranty period. The Company records amounts billed to customers for reimbursement of shipping and handling costs within revenue. Shipping and handling costs associated with outbound freight after control over a product has transferred to a customer are accounted for as fulfillment costs and are included in cost of goods sold. Sales taxes and other usage-based taxes are excluded from revenue.

Within the Electrical segment, certain businesses require a portion of the transaction price to be paid in advance of transfer of control. Advance payments are not considered a significant financing component as they are received less than one year before the related performance obligations are satisfied. In addition, in the Power segment, certain businesses offer annual maintenance service contracts that require payment at the beginning of the contract period. These payments are treated as a contract liability and are classified in Other accrued liabilities in the Condensed Consolidated Balance Sheet. Once control transfers to the customer and the Company meets the revenue recognition criteria, the deferred revenue is recognized in the Condensed Consolidated Statement of Income. The deferred revenue relating to the annual maintenance service contracts is recognized in the Condensed Consolidated Statement of Income on a straight line basis over the expected term of the contract.

Approximately two-thirds of the Company's net sales are to distributors who then sell directly into the residential, non-residential, industrial, electrical transmission and distribution and oil and gas end markets. In the Power segment, the businesses sell to distributors, with the majority of sales to the utility end markets. The Power businesses also sell directly into transmission and distribution utility markets.

The Company has certain arrangements that require us to estimate at the time of sale the amounts of variable consideration that should not be recorded as revenue as certain amounts are not expected to be collected from customers, as well as an estimate of the value of the product to be returned. The Company principally relies on historical experience, specific customer agreements and anticipated future trends to estimate these amounts at the time of shipment and to reduce the transaction price. These arrangements include sales discounts and allowances based on sales volumes, specific programs and special pricing allowances, and returned goods, as are customary in the electrical products industry. Customer returns have historically ranged from 1%-2% of gross sales.

The following table presents disaggregated revenue by business group (in millions) for the three months ended March 31, 2018:



	Electrical		Power		Total
Net sales
Hubbell Commercial and Industrial	$	215.5	$	—	$	215.5
Hubbell Construction and Energy	186.4		—		186.4
Hubbell Lighting	216.2		—		216.2
Hubbell Power Systems	—		373.1		373.1
Total net sales	$	618.1	$	373.1	$	991.2

The following table presents disaggregated revenue by geographic location (in millions) for the three months ended March 31, 2018 (on a geographic basis, the Company defines "international" as operations based outside of the United States and its possessions):



	Electrical		Power		Total
Net sales
United States	$	546.7	$	348.4	$	895.1
International	71.4		24.7		96.1
Total net sales	$	618.1	$	373.1	$	991.2

Contract Balances

Our contract liabilities consist of advance payments for products as well as deferred revenue on service obligations and extended warranties. The current portion of deferred revenue is included in Other accrued liabilities and the non-current portion of deferred revenue is included in Other non-current liabilities in the Condensed Consolidated Balance Sheet.

Contract liabilities were $17.5 million as of March 31, 2018 compared to $10.2 million as of December 31, 2017. The $7.3 million increase in our contract liabilities balance was primarily due to timing of advance payments on certain orders and the acquisition of Aclara, partially offset by the recognition of $5.0 million in revenue related to amounts that were recorded in contract liabilities at January 1, 2018. The Company has an immaterial amount of contract assets relating to performance obligations satisfied prior to payment that is recorded in Other long-term assets in the Condensed Consolidated Balance Sheet. Impairment losses recognized on our receivables and contract assets were immaterial in the first quarter of 2018. See Note 1 – Basis of Presentation and Note 3 – Business Acquisitions in the Notes to Condensed Consolidated Financial Statements for additional information.

Unsatisfied Performance Obligations

The Company has elected the practical expedient to disclose only the value of unsatisfied performance obligations for contracts with an original expected length greater than one year. Prior to the acquisition of Aclara, the majority of Hubbell's revenues resulted from sales of inventoried products with short periods of manufacture and delivery and thus are excluded from this disclosure. As of March 31, 2018, the Company had approximately $700 million of unsatisfied performance obligations for contracts with an original expected length of greater than one year, primarily relating to long-term contracts of the Aclara business (within the Power segment) to deliver and install meters. The Company expects that a majority of the unsatisfied performance obligations will be completed and recognized over the next 3-4 years.

Practical Expedients

We apply a practical expedient to expense costs as incurred for costs to obtain a contract when the amortization period would have been one year or less.

Business Acquisitions

3 Months Ended

Mar. 31, 2018

Business Combinations [Abstract]

Business Acquisitions

On February 2, 2018, the Company completed the acquisition of Aclara for approximately $1.1 billion. Aclara is a global 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 was structured as a merger in which Aclara became a wholly owned indirect subsidiary of the Company. Aclara's businesses have been added to the Power segment. The acquisition is intended to extend 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 financed the acquisition and related transactions with net proceeds from borrowings under a new unsecured term loan facility in the aggregate principal amount of $500 million, the issuance of 3.50% Senior Notes due 2028 in the aggregate principal amount of $450 million and issuances of commercial paper.

Preliminary Allocation of Consideration Transferred to Net Assets Acquired

The following table presents the preliminary determination of the fair value of identifiable assets acquired and liabilities assumed from the Company's acquisition of Aclara. The final determination of the fair value of certain assets and liabilities will be completed within the one year measurement period as required by the FASB ASC Topic 805, “Business Combinations.” As the Company finalizes the fair value of assets acquired and liabilities assumed, additional purchase price adjustments may be recorded during the measurement period in 2018. Fair value estimates are based on a complex series of judgments about future events and uncertainties and rely heavily on estimates and assumptions. The judgments used to determine the estimated fair value assigned to each class of assets acquired and liabilities assumed, as well as asset lives, can materially impact the Company's results of operations. The finalization of the purchase accounting assessment may result in a change in the valuation of assets acquired and liabilities assumed and may have a material impact on the Company's results of operations and financial position.

The following is a preliminary estimate of the assets acquired and the liabilities assumed by the Company in the merger, reconciled to the estimated acquisition consideration (in millions):



Accounts receivable	$	116.1
Inventories	76.9
Other current assets	11.7
Property, plant and equipment	31.5
Intangible assets	444.0
Accounts payable	(50.5		)
Other accrued liabilities	(67.5		)
Deferred tax liabilities	(72.3		)
Other non-current liabilities	(37.0		)
Noncontrolling interest	(2.5		)
Goodwill	669.0
Total Estimate of Consideration Transferred, Net of Cash Acquired	$	1,119.4

In connection with the merger, the Company recorded goodwill of $669.0 million, which is attributable primarily to expected synergies, expanded market opportunities, and other expected benefits that the Company believes will result from combining its operations with the operations of Aclara. The historical goodwill of Aclara resulting from their prior asset acquisitions is expected to be deductible for tax purposes. Any incremental goodwill created in the merger is not deductible for tax purposes. The goodwill resulting from the acquisition of Aclara is subject to potential significant changes as the purchase price allocation is completed. Goodwill has been allocated to the Power segment.

The preliminary purchase price allocation to identifiable intangible assets acquired is as follows:



	Estimated Fair Value		Weighted Average Estimated Useful Life
Patents, tradenames and trademarks	$	55.0	20.0
Customer relationships	204.0		17.0
Developed technology	185.0		13.0
Total	$	444.0

Customer relationship and developed technology intangible assets acquired are amortized using 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 asset's useful life.

Supplemental Pro-Forma Data

Aclara’s results of operations have been included in the Company's financial statements for the period subsequent to the completion of the acquisition on February 2, 2018. Aclara contributed sales of approximately $90.4 million and an operating loss of approximately $4.9 million for the period from the completion of the acquisition through March 31, 2018.

The following unaudited supplemental pro-forma information presents consolidated results as if the acquisition had been completed on January 1, 2017. Following that approach, for the purpose of the pro-forma results presented in the tables below, certain costs incurred by the company during the three months ended March 31, 2018 and December 31, 2017 have been reclassified out of their respective periods and into the pro-forma period ended March 31, 2017. Those reclassifications primarily include the following, which represent the amount of increase or (decrease) to reported results to arrive at the pro forma results. Per share amounts in 2018 reflect the reduction in the U.S. Federal corporate income tax rate from 35% to 21%:



(pre-tax in millions, except per share amounts)	Three Months Ended March 31,						Per Diluted Share
	2018			2017			2018			2017
Aclara transaction costs incurred in the first quarter of 2018⁽¹⁾	$	10.3		$	(10.3	)	$	0.15		$	(0.14	)
Aclara transaction costs incurred in the fourth quarter of 2017⁽¹⁾	—			(7.1		)	—			(0.11		)
Intangible amortization and inventory step up⁽²⁾	1.6			(16.9		)	0.02			(0.19		)
Interest expense⁽³⁾	$	(2.1	)	$	(7.2	)	$	(0.03	)	$	(0.08	)

⁽¹⁾ Aclara transaction costs incurred in the first quarter of 2018 are presented in the pro-forma March 31, 2017 period. The pro-forma March 31, 2017 period also includes transaction costs incurred by the Company during the fourth quarter of 2017.

⁽²⁾ Aclara intangible amortization and inventory step up amortization incurred in the first quarter of 2018 has been reclassified into the pro-forma March 31, 2017 period and increased to include three months of amortization expense. The pro-forma March 31, 2018 period includes three months of intangible amortization that would be incurred assuming the transaction had been completed on January 1, 2017.

⁽³⁾ Interest expense incurred in the first quarter of 2018, reflecting two months recognized in the quarter from the date of the acquisition, has been reclassified into the pro-forma March 31, 2017 period and increased to include three months of interest expense. The pro-forma March 31, 2018 period includes three months of interest expense that would be incurred assuming the transaction had been completed on January 1, 2017.

The pro-forma results were calculated by combining the results of the Company with the stand-alone results of Aclara for the pre-acquisition periods, as described above:



	Three Months Ended March 31,
	2018		2017
Net sales	$	1,037.9	$	959.2
Net income attributable to Hubbell	$	67.7	$	39.5
Earnings Per Share:
Basic	$	1.23	$	0.71
Diluted	$	1.22	$	0.71

The unaudited supplemental pro-forma financial information does not reflect the actual performance of Aclara in the periods presented and does not reflect the potential realization of cost savings relating to the integration of the two companies. Further, the pro-forma data should not be considered indicative of the results that would have occurred if the acquisition and related financing had been consummated on January 1, 2017, nor are they indicative of future results.

Segment Information

3 Months Ended

Mar. 31, 2018

Segment Reporting [Abstract]

Segment Information

The Company's reporting segments consist of the Electrical segment and the Power segment. The Electrical segment comprises businesses that sell stock and custom products including standard and special application wiring device products, rough-in electrical products, connector and grounding products, light fixtures and controls, components and assemblies for the natural gas distribution market as well as other electrical and communication equipment, some of which is designed such that it can also be used in harsh and hazardous locations primarily in the oil, gas (onshore and offshore) and mining industries. These products are primarily sold to electrical distributors who then sell directly into the residential, non-residential, industrial, electrical transmission and distribution, and oil and gas end markets. The Electrical segment comprises three business groups, which have been aggregated as they have similar long-term economic characteristics, customers and distribution channels, among other factors. The Power segment primarily serves the electric utility industry and comprises a wide variety of electrical distribution, transmission, and substation products with high voltage applications as well as telecommunication products and smart infrastructure solutions. The Aclara businesses have been added to the Power segment and are intended to extend the segment's capabilities into smart automation technologies, accelerate ongoing innovations efforts to address utility customer demand for data and integrated solutions, and expand the segment's reach to a broader set of utility customers. See Note 1 – Basis of Presentation and Note 3 – Business Acquisitions in the Notes to Condensed Consolidated Financial Statements for additional information. The following table sets forth financial information by business segment (in millions):



	Net Sales				Operating Income				Operating Income as a % of Net Sales
	2018		2017		2018		2017		2018		2017
Three Months Ended March 31,
Electrical	$	618.1	$	587.5	$	61.2	$	52.8	9.9	%	9.0	%
Power	373.1		264.8		38.4		55.0		10.3	%	20.8	%
TOTAL	$	991.2	$	852.3	$	99.6	$	107.8	10.0	%	12.6	%

Goodwill and Intangible Assets, net

3 Months Ended

Mar. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Intangible Assets, net

Changes in the carrying values of goodwill for the three months ended March 31, 2018, were as follows (in millions):



	Segment
	Electrical		Power		Total
BALANCE DECEMBER 31, 2017	$	717.6	$	371.4	$	1,089.0
Current year acquisitions (Note 3 – Business Acquisitions)	—		669.0		669.0
Foreign currency translation and prior year acquisitions	1.9		0.2		2.1
BALANCE MARCH 31, 2018	$	719.5	$	1,040.6	$	1,760.1

In the first three months of 2018, the Company completed one acquisition (Aclara) that was added to the Power segment. This acquisition has been accounted for as a business combination and has resulted in the recognition of $669.0 million of goodwill. See Note 3 – Business Acquisitions in the Notes to Condensed Consolidated Financial Statements for additional information.

The carrying value of other intangible assets included in Intangible assets, net in the Condensed Consolidated Balance Sheet is as follows (in millions):



	March 31, 2018					December 31, 2017
	Gross Amount		Accumulated Amortization			Gross Amount		Accumulated Amortization
Definite-lived:
Patents, tradenames and trademarks	$	206.5	$	(52.2	)	$	151.4	$	(50.1	)
Customer/agent relationships and other	850.5		(169.2		)	462.0		(156.7		)
Total	$	1,057.0	$	(221.4	)	$	613.4	$	(206.8	)
Indefinite-lived:
Tradenames and other	53.9		—			53.8		—
TOTAL	$	1,110.9	$	(221.4	)	$	667.2	$	(206.8	)

Amortization expense associated with definite-lived intangible assets was $15.4 million and $8.5 million for the three months ended March 31, 2018 and 2017, respectively. Future amortization expense associated with these intangible assets is expected to be $56.7 million for the remainder of 2018, $77.8 million in 2019, $76.2 million in 2020, $74.5 million in 2021, $66.1 million in 2022, and $59.5 million in 2023.

- 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

Other Accrued Liabilities

3 Months Ended

Mar. 31, 2018

Accrued Liabilities [Abstract]

Other Accrued Liabilities

Other accrued liabilities are composed of the following (in millions):



	March 31, 2018		December 31, 2017
Customer program incentives	$	27.0	$	41.2
Accrued income taxes	29.8		27.5
Contract liabilities - deferred revenue	17.5		10.2
Customer refund liability	17.5		—
Accrued warranties	30.4		14.0
Other	88.7		82.0
TOTAL	$	210.9	$	174.9

Total Equity

3 Months Ended

Mar. 31, 2018

Stockholders' Equity Note [Abstract]

Total Equity

Total equity is composed of the following (in millions, except per share amounts):



	March 31, 2018			December 31, 2017
Common stock, $.01 par value:
Common Stock – authorized 200.0 shares; issued and outstanding 54.8 and 54.9 shares	$	0.6		$	0.6
Additional paid-in capital	10.2			11.0
Retained earnings	1,908.9			1,892.4
Accumulated other comprehensive loss:
Pension and post retirement benefit plan adjustment, net of tax	(174.5		)	(176.5		)
Cumulative translation adjustment	(82.1		)	(91.9		)
Unrealized gain (loss) on investment, net of tax	(0.9		)	(0.6		)
Cash flow hedge gain (loss), net of tax	(0.2		)	(0.8		)
Total Accumulated other comprehensive loss	(257.7		)	(269.8		)
Hubbell shareholders’ equity	1,662.0			1,634.2
Noncontrolling interest	16.5			13.7
TOTAL EQUITY	$	1,678.5		$	1,647.9

A summary of the changes in equity for the three months ended March 31, 2018 and 2017 is provided below (in millions):



	Three Months Ended March 31,
	2018									2017
	Hubbell Shareholders’ Equity			Noncontrolling interest			Total Equity			Hubbell Shareholders’ Equity			Noncontrolling interest			Total Equity
EQUITY, JANUARY 1	$	1,634.2		$	13.7		$	1,647.9		$	1,592.8		$	10.4		$	1,603.2
Total comprehensive income	70.4			1.5			71.9			76.3			1.1			77.4
Stock-based compensation	5.1			—			5.1			4.2			—			4.2
ASC 606 adoption to retained earnings	0.6			—			0.6			—			—			—
Repurchase/surrender of shares of common stock	(6.1		)	—			(6.1		)	(55.9		)	—			(55.9		)
Issuance of shares related to directors’ deferred compensation, net	0.1			—			0.1			0.1			—			0.1
Dividends to noncontrolling interest	—			(1.1		)	(1.1		)	—			(1.4		)	(1.4		)
Aclara noncontrolling interest	—			2.4			2.4			—			—			—
Cash dividends declared	(42.3		)	—			(42.3		)	(38.8		)	—			(38.8		)
EQUITY, MARCH 31	$	1,662.0		$	16.5		$	1,678.5		$	1,578.7		$	10.1		$	1,588.8

The detailed components of total comprehensive income are presented in the Condensed Consolidated Statement of Comprehensive Income.

Accumulated Other Comprehensive Loss

3 Months Ended

Mar. 31, 2018

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 months ended March 31, 2018 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, 2017	$	(0.8	)	$	(0.6	)	$	(176.5	)	$	(91.9	)	$	(269.8	)
Other comprehensive income (loss) before reclassifications	0.4			(0.3		)	—			9.8			9.9
Amounts reclassified from accumulated other comprehensive loss	0.2			—			2.0			—			2.2
Current period other comprehensive income (loss)	0.6			(0.3		)	2.0			9.8			12.1
BALANCE AT MARCH 31, 2018	$	(0.2	)	$	(0.9	)	$	(174.5	)	$	(82.1	)	$	(257.7	)

A summary of the gain (loss) reclassifications out of Accumulated other comprehensive loss for the three months ended March 31, 2018 and 2017 is provided below (in millions):



Details about Accumulated Other Comprehensive Loss Components	Three Months Ended March 31, 2018			Three Months Ended March 31, 2017				Location of Gain (Loss) Reclassified into Income
Cash flow hedges gain (loss):
Forward exchange contracts	$	—		$	—			Net sales
	(0.2		)	(0.1		)		Cost of goods sold
	(0.2		)	(0.1		)		Total before tax
	—			—				Tax benefit (expense)
	$	(0.2	)	$	(0.1	)		Gain (loss) net of tax
Amortization of defined benefit pension and post retirement benefit items:
Prior-service costs	$	0.2		$	0.2		(a)
Actuarial gains/(losses)	(2.8		)	(2.8		)	(a)
	(2.6		)	(2.6		)		Total before tax
	0.6			0.9				Tax benefit (expense)
	$	(2.0	)	$	(1.7	)		Gain (loss) net of tax
Losses reclassified into earnings	$	(2.2	)	$	(1.8	)		Gain (loss) net of tax


(a)	These accumulated other comprehensive loss components are included in the computation of net periodic pension cost (see Note 12 – Pension and Other Benefits in the Notes to Condensed Consolidated Financial Statements for additional details).

Earnings Per Share

3 Months Ended

Mar. 31, 2018

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. Service-based and performance-based restricted stock awards granted by the Company are considered participating securities as these awards contain a non-forfeitable right to dividends.

The following table sets forth the computation of earnings per share for the three months ended March 31, 2018 and 2017 (in millions, except per share amounts):



	Three Months Ended March 31,
	2018			2017
Numerator:
Net income attributable to Hubbell	$	58.3		$	62.8
Less: Earnings allocated to participating securities	(0.2		)	(0.2		)
Net income available to common shareholders	$	58.1		$	62.6
Denominator:
Average number of common shares outstanding	54.7			55.2
Potential dilutive common shares	0.4			0.4
Average number of diluted shares outstanding	55.1			55.6
Earnings per share:
Basic	$	1.06		$	1.13
Diluted	$	1.05		$	1.13

The Company did not have outstanding any significant anti-dilutive securities during the three months ended March 31, 2018 and 2017.

Pension and Other Benefits

3 Months Ended

Mar. 31, 2018

Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]

Pension and Other Benefits

The following table sets forth the components of net pension and other benefit costs for the three months ended March 31, 2018 and 2017 (in millions):



	Pension Benefits						Other Benefits
	2018			2017			2018			2017
Three Months Ended March 31,
Service cost	$	1.1		$	1.5		$	—		$	—
Interest cost	8.6			9.2			0.2			0.3
Expected return on plan assets	(8.5		)	(8.5		)	—			—
Amortization of prior service cost	—			—			(0.2		)	(0.2		)
Amortization of actuarial losses	2.8			2.8			—			—
NET PERIODIC BENEFIT COST	$	4.0		$	5.0		$	—		$	0.1

Employer Contributions

Although not required by ERISA and the Internal Revenue Code, the Company may elect to make a voluntary contribution to its qualified domestic defined benefit pension plan in 2018. The Company anticipates making required contributions of approximately $1.9 million to its foreign pension plans during 2018, of which $0.5 million has been contributed through March 31, 2018.

Guarantees

3 Months Ended

Mar. 31, 2018

Standard Product Warranty Disclosure [Abstract]

Guarantees

The Company records a liability equal to the fair value of guarantees 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 March 31, 2018 and December 31, 2017, the fair value and maximum potential payment related to the Company’s guarantees were not material.

The Company offers product warranties that 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 during the three months ended March 31, 2018 and 2017 are set forth below (in millions):



	2018			2017
BALANCE AT JANUARY 1,	$	14.0		$	13.8
Provision^(a)	3.2			2.7
Expenditures/other	(4.5		)	(2.1		)
Acquisitions^(b)	44.4			—
BALANCE AT MARCH 31,	$	57.1		$	14.4

^(a) Refer to Note 7 – Other Accrued Liabilities and Note 8 – Other Non-Current Liabilities for a breakout of short-term and long-term warranties.

^(b) The acquisition amount disclosed relates to the Aclara acquisition. Refer to Note 3 – Business Acquisitions for additional information.

Fair Value Measurement

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurement

Investments

At March 31, 2018 and December 31, 2017, the Company had $57.1 million and $58.4 million, respectively, of available-for-sale securities, consisting of municipal bonds classified in Level 2 of the fair value hierarchy and an investment in the redeemable preferred stock of a privately-held electrical utility substation security provider classified in Level 3 of the fair value hierarchy. The Company also had $14.9 million of trading securities at March 31, 2018 and $13.8 million at December 31, 2017 that are carried on the balance sheet at fair value. Unrealized gains and losses associated with available-for-sale securities are reflected in Accumulated other comprehensive loss, net of tax, while unrealized gains and losses associated with trading securities are reflected in the results of operations.

Fair value measurements

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. 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 table shows, by level within the fair value hierarchy, our financial assets and liabilities that are accounted for at fair value on a recurring basis at March 31, 2018 and December 31, 2017 (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
March 31, 2018
Money market funds^(a)	$	55.8		$	—		$	—	$	55.8
Available for sale investments	—			53.0			4.1		57.1
Trading securities	14.9			—			—		14.9
Deferred compensation plan liabilities	(14.9		)	—			—		(14.9		)
Derivatives:
Forward exchange contracts-Assets^(b)	—			0.5			—		0.5
Forward exchange contracts-(Liabilities)^(c)	—			(0.3		)	—		(0.3		)
TOTAL	$	55.8		$	53.2		$	4.1	$	113.1

	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
December 31, 2017
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		)
TOTAL	$	126.9		$	53.8		$	4.1	$	184.8

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

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

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

The methods and assumptions used to estimate the Level 2 and Level 3 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.

Available-for-sale municipal bonds classified in Level 2 – 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 expected cash flows and the discount rate.

During the three months ended March 31, 2018 there were no transfers of financial assets or liabilities in or out of Level 1 or Level 2 of the fair value hierarchy. There were also no transfers in or out of Level 3 during that period.

Deferred compensation plans

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 the three months ended March 31, 2018 and 2017, the Company purchased $1.6 million of trading securities related to these deferred compensation plans. As a result of participant distributions, the Company sold $0.4 million of these trading securities during the three months ended March 31, 2018 and $0.3 million during the three months ended March 31, 2017. 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 forecasted 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, liability or forecasted transaction are recognized in income. Derivative assets and derivative liabilities are not offset in the Condensed Consolidated Balance Sheet.

In 2018 and 2017, the Company entered into a series of forward exchange contracts to purchase U.S. dollars in order to hedge exposure to fluctuating rates of exchange for both anticipated inventory purchases and forecasted sales by its subsidiaries that transact business in Canada. As of March 31, 2018, the Company had 43 individual forward exchange contracts for an aggregate notional amount of $37.0 million, having various expiration dates through March 2019. 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 the three months ended March 31, 2018 and 2017 (in millions):



	Derivative Gain/(Loss) Recognized in Accumulated Other Comprehensive Income (net of tax)					Location of Gain/(Loss) Reclassified into Income	Gain/(Loss) Reclassified into Earnings Effective Portion (net of tax)
Derivative Instrument	2018		2017			(Effective Portion)	2018			2017
Forward exchange contract	$	0.4	$	(0.2	)	Net sales	$	—		$	—
						Cost of goods sold	$	(0.2	)	$	(0.1	)

Hedge ineffectiveness was immaterial with respect to the forward exchange cash flow hedges during the three months ended March 31, 2018 and 2017.

Long Term Debt

As of March 31, 2018 and December 31, 2017, the estimated fair value of the long-term debt was $1,920.6 million and $1,013.2 million, respectively, using quoted market prices in active markets for similar liabilities (Level 2).

- 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

Commitment and Contingencies

3 Months Ended

Mar. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

NOTE 15 Commitments and Contingencies

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.

Restructuring Costs and Other

3 Months Ended

Mar. 31, 2018

Restructuring and Related Activities [Abstract]

Restructuring Costs and Other

In the three months ended March 31, 2018, we incurred costs for restructuring actions initiated in 2018 as well as costs for 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 include 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 liability associated with the withdrawal from a multi-employer pension plan. The 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 reporting segments and the location of the costs in the Condensed Consolidated Statement of Income for the three months ended March 31, 2018 and 2017 is as follows (in millions):



	Three Months Ended March 31,
	2018		2017		2018			2017		2018		2017
	Cost of goods sold				Selling & administrative expense					Total
Electrical Segment	$	0.8	$	3.7	$	(0.1	)	$	1.0	$	0.7	$	4.7
Power Segment	—		0.5		—			0.3		—		0.8
Total Pre-Tax Restructuring Costs	$	0.8	$	4.2	$	(0.1	)	$	1.3	$	0.7	$	5.5

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



	Beginning Accrued Restructuring Balance 1/1/18		Pre-tax Restructuring Costs			Utilization and Foreign Exchange			Ending Accrued Restructuring Balance 3/31/2018
2018 Restructuring Actions
Severance	$	—	$	0.2		$	—		$	0.2
Asset write-downs	—		—			—			—
Facility closure and other costs	—		0.1			—			0.1
Total 2018 Restructuring Actions	$	—	$	0.3		$	—		$	0.3
2017 and Prior Restructuring Actions
Severance	$	5.4	$	(0.2	)	$	(1.0	)	$	4.2
Asset write-downs	—		—			—			—
Facility closure and other costs^(a)	15.5		0.6			(1.7		)	14.4
Total 2017 and Prior Restructuring Actions	$	20.9	$	0.4		$	(2.7	)	$	18.6
Total Restructuring Actions	$	20.9	$	0.7		$	(2.7	)	$	18.9

(a) Facility closure and other costs as of 1/1/18 and 3/31/18 include a liability of approximately $12.5 million associated with the withdrawal from a multi-employer pension plan as a result of a restructuring action.

The actual costs incurred and total expected cost of our on-going restructuring actions are as follows (in millions):



	Total expected costs		Costs incurred during 2017		Costs incurred during first three months of 2018			Remaining costs at 3/31/2018
2018 Restructuring Actions
Electrical Segment	$	4.2	$	—	$	0.2		$	4.0
Power Segment	0.1		—		0.1			—
Total 2018 Restructuring Actions	$	4.3	$	—	$	0.3		$	4.0
2017 and Prior Restructuring Actions
Electrical Segment	$	19.7	$	16.9	$	0.5		$	2.3
Power Segment	3.8		3.4		(0.1		)	0.5
Total 2017 and Prior Restructuring Actions	$	23.5	$	20.3	$	0.4		$	2.8
Total Restructuring Actions	$	27.8	$	20.3	$	0.7		$	6.8

Long Term Debt and Financing Arrangements Long Term Debt and Financing Arrangements

3 Months Ended

Mar. 31, 2018

Debt Disclosure [Abstract]

Long Term Debt and Financing Arrangements

Long-term debt consists of the following (in millions):



	Maturity	March 31, 2018		December 31, 2017
Senior notes at 3.625%	2022	$	298.0	$	297.9
Senior notes at 3.35%	2026	394.6		394.4
Senior notes at 3.15%	2027	294.9		294.8
Senior notes at 3.50%	2028	442.8		—
Term loan, net of current portion of $25 million	2023	472.9		—
TOTAL LONG-TERM DEBT ^(a)		$	1,903.2	$	987.1

^(a) Long-term debt is presented net of debt issuance costs and unamortized discounts.

In February 2018, the Company completed a public offering of $450 million of senior, unsecured, notes maturing in February 2028 and bearing interest at a fixed rate of 3.50% (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 callable at any time at specific prices and are only subject to accelerated payment prior to maturity upon customary events of a default 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.

In January 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. The interest rate applicable to borrowings under the Term Loan Agreement is generally either 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 sole 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. The Company was in compliance with this covenant as of March 31, 2018.

In January 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 of Aclara, the Company terminated all commitments under the Company's previous 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 adjusted LIBOR plus an applicable margin (determined by reference to a ratings based grid) or the alternate base rate. The 2018 Credit Facility expires in February 2023. The sole 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 Company was in compliance with this covenant as of March 31, 2018. As of March 31, 2018, the 2018 Credit Facility was undrawn.

At December 31, 2017, the Company had $68.1 million of short-term debt outstanding. The Company had $177.5 million short-term debt outstanding at March 31, 2018, which consisted primarily of commercial paper.

Basis of Presentation (Policies)	3 Months Ended
Basis of Presentation (Policies)	Mar. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	The accompanying unaudited condensed consolidated financial statements of Hubbell Incorporated (“Hubbell”, the “Company”, “registrant”, “we”, “our” or “us”, which references include its divisions and subsidiaries) have been prepared in accordance with generally accepted accounting principles (“GAAP”) for interim financial information. Accordingly, they do not include all of the information and footnotes required by United States of America (“U.S.”) GAAP for audited financial statements. In the opinion of management, all adjustments consisting only of normal recurring adjustments considered necessary for a fair statement of the results of the periods presented have been included. Operating results for the three months ended March 31, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018. The balance sheet at December 31, 2017 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the U.S. for complete financial statements. For further information, refer to the consolidated financial statements and footnotes thereto included in the Hubbell Incorporated Annual Report on Form 10-K for the year ended December 31, 2017.
Recent Accounting Pronouncements	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 Company will adopt the standard as of January 1, 2019. 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 our results of operations. In May 2014, the FASB issued an Accounting Standards Update (ASU 2014-09) related to new revenue recognition guidance (ASC 606) 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. Effective January 1, 2018, the Company adopted the requirements of ASC 606 using the modified retrospective approach. The Company applied the guidance to all contracts and recognized a cumulative effect adjustment to Retained Earnings as of January, 1, 2018 of $0.6 million. The impacts to the financial statements are primarily related to balance sheet classification, including amounts associated with the change in balance sheet classification of the sales returns reserves, while the impacts on the income statement reflect the change in classification of restocking fees. Recent Accounting Pronouncements In February 2018, the Financial Accounting Standards Board (“FASB”) issued an Accounting Standards Update (ASU 2018-02) relating to the reclassification of certain tax effects from accumulated other comprehensive income/(loss). The new guidance allows an entity to reclassify the income tax effects of the Public Law 115-97 "An Act to Provide Reconciliation Pursuant to Titles II and V of the Concurrent Resolution on the Budget for Fiscal Year 2018", commonly known as the Tax Cuts and Job Act of 2017 ("TCJA") on items within accumulated other comprehensive income/(loss) to retained earnings. This new guidance is effective for fiscal years beginning after December 15, 2018, with early adoption permitted. The new standard must be adopted retrospectively to each period in which the effect of the change in the U.S. federal corporate income tax rate in the TCJA is recognized. The Company is currently assessing the impact of adopting this standard on its financial statements. In response to the enactment of the TCJA, the Securities and Exchange Commission’s Office of the Chief Accountant published Staff Accounting Bulletin 118 ("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 TCJA 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, Income Taxes, (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 the fourth quarter of 2017, we recognized a provisional tax amount of approximately $57 million as a component of income tax expense from continuing operations for certain one-time items related to the TCJA for which we were able to determine a reasonable estimate. During the first quarter of 2018, the Company did not record any material adjustment to the provisional amounts recorded in the fourth quarter of 2017 or include a provisional amount for the income tax effects of any further repatriation of our unremitted foreign earnings as we continue to obtain, prepare, and analyze information and evaluate legislative and authoritative guidance being issued. In March 2017, the FASB issued an Accounting Standards Update (ASU 2017-07) relating to the presentation of net periodic pension costs and net periodic post-retirement benefit cost. The new guidance requires the service 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 components to be reported outside of operating income. The Company adopted the requirements of the new standard in the first quarter of 2018 and applied the guidance on a retrospective basis, as required by the standard.

Basis of Presentation (Tables)

3 Months Ended

Mar. 31, 2018

Accounting Policies [Abstract]

Schedule of new accounting pronouncements and changes in accounting principles

The impact to our financial statements for the quarter ended March 31, 2018 was as follows (in millions):



	For the Period Ended March 31, 2018
Income Statement	As Reported		Balances Without Adoption of ASC 606		Effect of Adoption Higher/(Lower)
Net sales	$	991.2	$	990.4	$	0.8

Costs and expenses
Cost of goods sold	$	708.3	$	707.5	$	0.8



	For the Period Ended March 31, 2018
Balance Sheet	As Reported		Balances Without Adoption of ASC 606		Effect of Adoption Higher/(Lower)
ASSETS
Accounts receivable, net	$	704.0	$	685.5	$	(18.5	)
Inventories, net	714.3		725.8		11.5
Other current assets	70.7		59.9		(10.8		)
Total Assets	$	4,975.4	$	4,957.6	$	(17.8	)

LIABILITIES
Other accrued liabilities	$	210.9	$	193.7	$	(17.2	)
Total Liabilities	$	3,296.9	$	3,279.7	$	(17.2	)

EQUITY
Retained Earnings	$	1,908.9	$	1,908.3	$	(0.6	)
Total Equity	$	1,678.5	$	1,677.9	$	(0.6	)

The impact to our fiscal quarters and year-ended 2017 is shown in the table below (in millions):



	Three Months Ended												Twelve Months Ended
(in millions, except per share amounts)	Dec 31, 2017			Sep 30, 2017			Jun 30, 2017			Mar 31, 2017			Dec 31, 2017
Cost of goods sold	$	(0.9	)	$	(0.8	)	$	(0.8	)	$	(0.8	)	$	(3.3	)
Selling & administrative expenses	(2.9		)	(3.0		)	(3.0		)	(2.9		)	(11.8		)
Total operating expenses	(3.8		)	(3.8		)	(3.8		)	(3.7		)	(15.1		)
Operating income	3.8			3.8			3.8			3.7			15.1
Total other expense	(3.8		)	(3.8		)	(3.8		)	(3.7		)	(15.1		)
Net income	$	—		$	—		$	—		$	—		$	—

Revenue (Tables)

3 Months Ended

Mar. 31, 2018

Revenue from Contract with Customer [Abstract]

Schedule of disaggregated revenue by business group

The following table presents disaggregated revenue by business group (in millions) for the three months ended March 31, 2018:



	Electrical		Power		Total
Net sales
Hubbell Commercial and Industrial	$	215.5	$	—	$	215.5
Hubbell Construction and Energy	186.4		—		186.4
Hubbell Lighting	216.2		—		216.2
Hubbell Power Systems	—		373.1		373.1
Total net sales	$	618.1	$	373.1	$	991.2



	Electrical		Power		Total
Net sales
United States	$	546.7	$	348.4	$	895.1
International	71.4		24.7		96.1
Total net sales	$	618.1	$	373.1	$	991.2

Business Acquisitions (Tables)

3 Months Ended

Mar. 31, 2018

Business Combinations [Abstract]

Summary of preliminary estimate of the assets acquired and liabilities assumed

The following is a preliminary estimate of the assets acquired and the liabilities assumed by the Company in the merger, reconciled to the estimated acquisition consideration (in millions):



Accounts receivable	$	116.1
Inventories	76.9
Other current assets	11.7
Property, plant and equipment	31.5
Intangible assets	444.0
Accounts payable	(50.5		)
Other accrued liabilities	(67.5		)
Deferred tax liabilities	(72.3		)
Other non-current liabilities	(37.0		)
Noncontrolling interest	(2.5		)
Goodwill	669.0
Total Estimate of Consideration Transferred, Net of Cash Acquired	$	1,119.4

Schedule of preliminary purchase price allocation to identified intangible assets acquired

The preliminary purchase price allocation to identifiable intangible assets acquired is as follows:



	Estimated Fair Value		Weighted Average Estimated Useful Life
Patents, tradenames and trademarks	$	55.0	20.0
Customer relationships	204.0		17.0
Developed technology	185.0		13.0
Total	$	444.0

Pro-forma nonrecurring adjustments



(pre-tax in millions, except per share amounts)	Three Months Ended March 31,						Per Diluted Share
	2018			2017			2018			2017
Aclara transaction costs incurred in the first quarter of 2018⁽¹⁾	$	10.3		$	(10.3	)	$	0.15		$	(0.14	)
Aclara transaction costs incurred in the fourth quarter of 2017⁽¹⁾	—			(7.1		)	—			(0.11		)
Intangible amortization and inventory step up⁽²⁾	1.6			(16.9		)	0.02			(0.19		)
Interest expense⁽³⁾	$	(2.1	)	$	(7.2	)	$	(0.03	)	$	(0.08	)

Summary of pro forma information



(pre-tax in millions, except per share amounts)	Three Months Ended March 31,						Per Diluted Share
	2018			2017			2018			2017
Aclara transaction costs incurred in the first quarter of 2018⁽¹⁾	$	10.3		$	(10.3	)	$	0.15		$	(0.14	)
Aclara transaction costs incurred in the fourth quarter of 2017⁽¹⁾	—			(7.1		)	—			(0.11		)
Intangible amortization and inventory step up⁽²⁾	1.6			(16.9		)	0.02			(0.19		)
Interest expense⁽³⁾	$	(2.1	)	$	(7.2	)	$	(0.03	)	$	(0.08	)

The pro-forma results were calculated by combining the results of the Company with the stand-alone results of Aclara for the pre-acquisition periods, as described above:



	Three Months Ended March 31,
	2018		2017
Net sales	$	1,037.9	$	959.2
Net income attributable to Hubbell	$	67.7	$	39.5
Earnings Per Share:
Basic	$	1.23	$	0.71
Diluted	$	1.22	$	0.71

Segment Information (Tables)

3 Months Ended

Mar. 31, 2018

Segment Reporting [Abstract]

Summary of segment information

The following table sets forth financial information by business segment (in millions):



	Net Sales				Operating Income				Operating Income as a % of Net Sales
	2018		2017		2018		2017		2018		2017
Three Months Ended March 31,
Electrical	$	618.1	$	587.5	$	61.2	$	52.8	9.9	%	9.0	%
Power	373.1		264.8		38.4		55.0		10.3	%	20.8	%
TOTAL	$	991.2	$	852.3	$	99.6	$	107.8	10.0	%	12.6	%

Inventories, net (Tables)

3 Months Ended

Mar. 31, 2018

Inventory, Net, Items Net of Reserve Alternative [Abstract]

Schedule of inventories, net

Inventories, net are composed of the following (in millions):



	March 31, 2018			December 31, 2017
Raw material	$	245.0		$	190.0
Work-in-process	117.9			115.8
Finished goods	412.7			390.5
	775.6			696.3
Excess of FIFO over LIFO cost basis	(61.3		)	(61.6		)
TOTAL	$	714.3		$	634.7

Goodwill and Intangible Assets, net (Tables)

3 Months Ended

Mar. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Summary of changes in goodwill

Changes in the carrying values of goodwill for the three months ended March 31, 2018, were as follows (in millions):



	Segment
	Electrical		Power		Total
BALANCE DECEMBER 31, 2017	$	717.6	$	371.4	$	1,089.0
Current year acquisitions (Note 3 – Business Acquisitions)	—		669.0		669.0
Foreign currency translation and prior year acquisitions	1.9		0.2		2.1
BALANCE MARCH 31, 2018	$	719.5	$	1,040.6	$	1,760.1

Schedule of intangible assets

The carrying value of other intangible assets included in Intangible assets, net in the Condensed Consolidated Balance Sheet is as follows (in millions):



	March 31, 2018					December 31, 2017
	Gross Amount		Accumulated Amortization			Gross Amount		Accumulated Amortization
Definite-lived:
Patents, tradenames and trademarks	$	206.5	$	(52.2	)	$	151.4	$	(50.1	)
Customer/agent relationships and other	850.5		(169.2		)	462.0		(156.7		)
Total	$	1,057.0	$	(221.4	)	$	613.4	$	(206.8	)
Indefinite-lived:
Tradenames and other	53.9		—			53.8		—
TOTAL	$	1,110.9	$	(221.4	)	$	667.2	$	(206.8	)

Total Equity (Tables)

3 Months Ended

Mar. 31, 2018

Stockholders' Equity Note [Abstract]

Schedule of stockholders equity

A summary of the changes in equity for the three months ended March 31, 2018 and 2017 is provided below (in millions):



	Three Months Ended March 31,
	2018									2017
	Hubbell Shareholders’ Equity			Noncontrolling interest			Total Equity			Hubbell Shareholders’ Equity			Noncontrolling interest			Total Equity
EQUITY, JANUARY 1	$	1,634.2		$	13.7		$	1,647.9		$	1,592.8		$	10.4		$	1,603.2
Total comprehensive income	70.4			1.5			71.9			76.3			1.1			77.4
Stock-based compensation	5.1			—			5.1			4.2			—			4.2
ASC 606 adoption to retained earnings	0.6			—			0.6			—			—			—
Repurchase/surrender of shares of common stock	(6.1		)	—			(6.1		)	(55.9		)	—			(55.9		)
Issuance of shares related to directors’ deferred compensation, net	0.1			—			0.1			0.1			—			0.1
Dividends to noncontrolling interest	—			(1.1		)	(1.1		)	—			(1.4		)	(1.4		)
Aclara noncontrolling interest	—			2.4			2.4			—			—			—
Cash dividends declared	(42.3		)	—			(42.3		)	(38.8		)	—			(38.8		)
EQUITY, MARCH 31	$	1,662.0		$	16.5		$	1,678.5		$	1,578.7		$	10.1		$	1,588.8

Total equity is composed of the following (in millions, except per share amounts):



	March 31, 2018			December 31, 2017
Common stock, $.01 par value:
Common Stock – authorized 200.0 shares; issued and outstanding 54.8 and 54.9 shares	$	0.6		$	0.6
Additional paid-in capital	10.2			11.0
Retained earnings	1,908.9			1,892.4
Accumulated other comprehensive loss:
Pension and post retirement benefit plan adjustment, net of tax	(174.5		)	(176.5		)
Cumulative translation adjustment	(82.1		)	(91.9		)
Unrealized gain (loss) on investment, net of tax	(0.9		)	(0.6		)
Cash flow hedge gain (loss), net of tax	(0.2		)	(0.8		)
Total Accumulated other comprehensive loss	(257.7		)	(269.8		)
Hubbell shareholders’ equity	1,662.0			1,634.2
Noncontrolling interest	16.5			13.7
TOTAL EQUITY	$	1,678.5		$	1,647.9

Accumulated Other Comprehensive Loss (Tables)

3 Months Ended

Mar. 31, 2018

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

Schedule of accumulated other comprehensive income loss

A summary of the changes in Accumulated other comprehensive loss (net of tax) for the three months ended March 31, 2018 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, 2017	$	(0.8	)	$	(0.6	)	$	(176.5	)	$	(91.9	)	$	(269.8	)
Other comprehensive income (loss) before reclassifications	0.4			(0.3		)	—			9.8			9.9
Amounts reclassified from accumulated other comprehensive loss	0.2			—			2.0			—			2.2
Current period other comprehensive income (loss)	0.6			(0.3		)	2.0			9.8			12.1
BALANCE AT MARCH 31, 2018	$	(0.2	)	$	(0.9	)	$	(174.5	)	$	(82.1	)	$	(257.7	)

Reclassifications out of accumulated other comprehensive income

A summary of the gain (loss) reclassifications out of Accumulated other comprehensive loss for the three months ended March 31, 2018 and 2017 is provided below (in millions):



Details about Accumulated Other Comprehensive Loss Components	Three Months Ended March 31, 2018			Three Months Ended March 31, 2017				Location of Gain (Loss) Reclassified into Income
Cash flow hedges gain (loss):
Forward exchange contracts	$	—		$	—			Net sales
	(0.2		)	(0.1		)		Cost of goods sold
	(0.2		)	(0.1		)		Total before tax
	—			—				Tax benefit (expense)
	$	(0.2	)	$	(0.1	)		Gain (loss) net of tax
Amortization of defined benefit pension and post retirement benefit items:
Prior-service costs	$	0.2		$	0.2		(a)
Actuarial gains/(losses)	(2.8		)	(2.8		)	(a)
	(2.6		)	(2.6		)		Total before tax
	0.6			0.9				Tax benefit (expense)
	$	(2.0	)	$	(1.7	)		Gain (loss) net of tax
Losses reclassified into earnings	$	(2.2	)	$	(1.8	)		Gain (loss) net of tax


(a)	These accumulated other comprehensive loss components are included in the computation of net periodic pension cost (see Note 12 – Pension and Other Benefits in the Notes to Condensed Consolidated Financial Statements for additional details).

Earnings Per Share (Tables)

3 Months Ended

Mar. 31, 2018

Earnings Per Share [Abstract]

Summary of the computation of earnings per share

The following table sets forth the computation of earnings per share for the three months ended March 31, 2018 and 2017 (in millions, except per share amounts):



	Three Months Ended March 31,
	2018			2017
Numerator:
Net income attributable to Hubbell	$	58.3		$	62.8
Less: Earnings allocated to participating securities	(0.2		)	(0.2		)
Net income available to common shareholders	$	58.1		$	62.6
Denominator:
Average number of common shares outstanding	54.7			55.2
Potential dilutive common shares	0.4			0.4
Average number of diluted shares outstanding	55.1			55.6
Earnings per share:
Basic	$	1.06		$	1.13
Diluted	$	1.05		$	1.13

Pension and Other Benefits (Tables)

3 Months Ended

Mar. 31, 2018

Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]

Schedule of net pension and other benefit costs

The following table sets forth the components of net pension and other benefit costs for the three months ended March 31, 2018 and 2017 (in millions):



	Pension Benefits						Other Benefits
	2018			2017			2018			2017
Three Months Ended March 31,
Service cost	$	1.1		$	1.5		$	—		$	—
Interest cost	8.6			9.2			0.2			0.3
Expected return on plan assets	(8.5		)	(8.5		)	—			—
Amortization of prior service cost	—			—			(0.2		)	(0.2		)
Amortization of actuarial losses	2.8			2.8			—			—
NET PERIODIC BENEFIT COST	$	4.0		$	5.0		$	—		$	0.1

Guarantees (Tables)

3 Months Ended

Mar. 31, 2018

Standard Product Warranty Disclosure [Abstract]

Schedule of product warranty liability

Changes in the accrual for product warranties during the three months ended March 31, 2018 and 2017 are set forth below (in millions):



	2018			2017
BALANCE AT JANUARY 1,	$	14.0		$	13.8
Provision^(a)	3.2			2.7
Expenditures/other	(4.5		)	(2.1		)
Acquisitions^(b)	44.4			—
BALANCE AT MARCH 31,	$	57.1		$	14.4

^(a) Refer to Note 7 – Other Accrued Liabilities and Note 8 – Other Non-Current Liabilities for a breakout of short-term and long-term warranties.

^(b) The acquisition amount disclosed relates to the Aclara acquisition. Refer to Note 3 – Business Acquisitions for additional information.

Fair Value Measurement (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Summary of financial assets and liability by fair value hierarchy level



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
March 31, 2018
Money market funds^(a)	$	55.8		$	—		$	—	$	55.8
Available for sale investments	—			53.0			4.1		57.1
Trading securities	14.9			—			—		14.9
Deferred compensation plan liabilities	(14.9		)	—			—		(14.9		)
Derivatives:
Forward exchange contracts-Assets^(b)	—			0.5			—		0.5
Forward exchange contracts-(Liabilities)^(c)	—			(0.3		)	—		(0.3		)
TOTAL	$	55.8		$	53.2		$	4.1	$	113.1

	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
December 31, 2017
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		)
TOTAL	$	126.9		$	53.8		$	4.1	$	184.8

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

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

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

Summary of the results of cash flow hedging relationships

The following table summarizes the results of cash flow hedging relationships for the three months ended March 31, 2018 and 2017 (in millions):



	Derivative Gain/(Loss) Recognized in Accumulated Other Comprehensive Income (net of tax)					Location of Gain/(Loss) Reclassified into Income	Gain/(Loss) Reclassified into Earnings Effective Portion (net of tax)
Derivative Instrument	2018		2017			(Effective Portion)	2018			2017
Forward exchange contract	$	0.4	$	(0.2	)	Net sales	$	—		$	—
						Cost of goods sold	$	(0.2	)	$	(0.1	)

Hedge ineffectiveness was immaterial with respect to the forward exchange cash flow hedges during the three months ended March 31, 2018 and 2017.

Restructuring Costs and Other (Tables)

3 Months Ended

Mar. 31, 2018

Restructuring and Related Activities [Abstract]

Summary of restructuring costs



	Three Months Ended March 31,
	2018		2017		2018			2017		2018		2017
	Cost of goods sold				Selling & administrative expense					Total
Electrical Segment	$	0.8	$	3.7	$	(0.1	)	$	1.0	$	0.7	$	4.7
Power Segment	—		0.5		—			0.3		—		0.8
Total Pre-Tax Restructuring Costs	$	0.8	$	4.2	$	(0.1	)	$	1.3	$	0.7	$	5.5

The actual costs incurred and total expected cost of our on-going restructuring actions are as follows (in millions):



	Total expected costs		Costs incurred during 2017		Costs incurred during first three months of 2018			Remaining costs at 3/31/2018
2018 Restructuring Actions
Electrical Segment	$	4.2	$	—	$	0.2		$	4.0
Power Segment	0.1		—		0.1			—
Total 2018 Restructuring Actions	$	4.3	$	—	$	0.3		$	4.0
2017 and Prior Restructuring Actions
Electrical Segment	$	19.7	$	16.9	$	0.5		$	2.3
Power Segment	3.8		3.4		(0.1		)	0.5
Total 2017 and Prior Restructuring Actions	$	23.5	$	20.3	$	0.4		$	2.8
Total Restructuring Actions	$	27.8	$	20.3	$	0.7		$	6.8

Schedule of restructuring reserve by type of cost

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



	Beginning Accrued Restructuring Balance 1/1/18		Pre-tax Restructuring Costs			Utilization and Foreign Exchange			Ending Accrued Restructuring Balance 3/31/2018
2018 Restructuring Actions
Severance	$	—	$	0.2		$	—		$	0.2
Asset write-downs	—		—			—			—
Facility closure and other costs	—		0.1			—			0.1
Total 2018 Restructuring Actions	$	—	$	0.3		$	—		$	0.3
2017 and Prior Restructuring Actions
Severance	$	5.4	$	(0.2	)	$	(1.0	)	$	4.2
Asset write-downs	—		—			—			—
Facility closure and other costs^(a)	15.5		0.6			(1.7		)	14.4
Total 2017 and Prior Restructuring Actions	$	20.9	$	0.4		$	(2.7	)	$	18.6
Total Restructuring Actions	$	20.9	$	0.7		$	(2.7	)	$	18.9

Long Term Debt and Financing Arrangements (Tables)

3 Months Ended

Mar. 31, 2018

Debt Disclosure [Abstract]

Schedule of Long Term Debt

Long-term debt consists of the following (in millions):



	Maturity	March 31, 2018		December 31, 2017
Senior notes at 3.625%	2022	$	298.0	$	297.9
Senior notes at 3.35%	2026	394.6		394.4
Senior notes at 3.15%	2027	294.9		294.8
Senior notes at 3.50%	2028	442.8		—
Term loan, net of current portion of $25 million	2023	472.9		—
TOTAL LONG-TERM DEBT ^(a)		$	1,903.2	$	987.1

^(a) Long-term debt is presented net of debt issuance costs and unamortized discounts.

Basis of Presentation (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended
Basis of Presentation (Details) - USD ($) $ in Millions	Feb. 02, 2018	Feb. 28, 2018	Dec. 31, 2017	Mar. 31, 2018
Business Acquisition [Line Items]
Tax cuts and jobs act of 2017, provisional income tax expense			$ 57
Aclara
Business Acquisition [Line Items]
Consideration transferred to acquire business	$ 1,100	$ 1,100
Pro Forma \| Accounting Standards Update 2016-02
Business Acquisition [Line Items]
Lease, right-of-use asset (less than)				$ 100

Basis of Presentation Basis of Presentation - Schedule of New Accounting Pronouncements and Changes (Details) - USD ($) $ in Millions	3 Months Ended					12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Selling & administrative expenses	$ 183.3				$ 154.8
Operating Income	99.6				107.8
Net income	58.3				62.8
Net sales	991.2				852.3
Cost of goods sold	708.3				589.7
Accounts receivable, net	704.0	$ 540.3				$ 540.3
Inventories, net	714.3	634.7				634.7
Other current assets	70.7	39.6				39.6
Total Assets	4,975.4	3,720.6				3,720.6
Other accrued liabilities	210.9	174.9				174.9
Total Liabilities	3,296.9	2,072.7				2,072.7
Retained Earnings	1,908.9	1,892.4				1,892.4
Total Equity	1,678.5	1,647.9			1,588.8	1,647.9	$ 1,603.2
Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of goods sold		(0.9)	$ (0.8)	$ (0.8)	(0.8)	(3.3)
Selling & administrative expenses		(2.9)	(3.0)	(3.0)	(2.9)	(11.8)
Total operating expenses		(3.8)	(3.8)	(3.8)	(3.7)	(15.1)
Operating Income		3.8	3.8	3.8	3.7	15.1
Total other expense		(3.8)	(3.8)	(3.8)	(3.7)	(15.1)
Net income		$ 0.0	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Balances Without Adoption of ASC 606 \| Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net sales	990.4
Cost of goods sold	707.5
Accounts receivable, net	685.5
Inventories, net	725.8
Other current assets	59.9
Total Assets	4,957.6
Other accrued liabilities	193.7
Total Liabilities	3,279.7
Retained Earnings	1,908.3
Total Equity	1,677.9
Effect of Adoption Higher/(Lower) \| Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net sales	0.8
Cost of goods sold	0.8
Accounts receivable, net	(18.5)
Inventories, net	11.5
Other current assets	(10.8)
Total Assets	(17.8)
Other accrued liabilities	(17.2)
Total Liabilities	(17.2)
Retained Earnings	(0.6)
Total Equity	$ (0.6)

Revenue - Disaggregation of Revenue (Details) $ in Millions	3 Months Ended
Revenue - Disaggregation of Revenue (Details) $ in Millions	Mar. 31, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Total net sales	$ 991.2
United States
Disaggregation of Revenue [Line Items]
Total net sales	895.1
International
Disaggregation of Revenue [Line Items]
Total net sales	96.1
Hubbell Commercial and Industrial
Disaggregation of Revenue [Line Items]
Total net sales	215.5
Hubbell Construction and Energy
Disaggregation of Revenue [Line Items]
Total net sales	186.4
Hubbell Lighting
Disaggregation of Revenue [Line Items]
Total net sales	216.2
Hubbell Power Systems
Disaggregation of Revenue [Line Items]
Total net sales	373.1
Electrical
Disaggregation of Revenue [Line Items]
Total net sales	618.1
Electrical \| United States
Disaggregation of Revenue [Line Items]
Total net sales	546.7
Electrical \| International
Disaggregation of Revenue [Line Items]
Total net sales	71.4
Electrical \| Hubbell Commercial and Industrial
Disaggregation of Revenue [Line Items]
Total net sales	215.5
Electrical \| Hubbell Construction and Energy
Disaggregation of Revenue [Line Items]
Total net sales	186.4
Electrical \| Hubbell Lighting
Disaggregation of Revenue [Line Items]
Total net sales	216.2
Electrical \| Hubbell Power Systems
Disaggregation of Revenue [Line Items]
Total net sales	0.0
Power
Disaggregation of Revenue [Line Items]
Total net sales	373.1
Power \| United States
Disaggregation of Revenue [Line Items]
Total net sales	348.4
Power \| International
Disaggregation of Revenue [Line Items]
Total net sales	24.7
Power \| Hubbell Commercial and Industrial
Disaggregation of Revenue [Line Items]
Total net sales	0.0
Power \| Hubbell Construction and Energy
Disaggregation of Revenue [Line Items]
Total net sales	0.0
Power \| Hubbell Lighting
Disaggregation of Revenue [Line Items]
Total net sales	0.0
Power \| Hubbell Power Systems
Disaggregation of Revenue [Line Items]
Total net sales	$ 373.1

Revenue - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
Revenue - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Percentage of revenue from service contracts and post-shipment obligations (less than)	3.00%
Percentage of sales to distributors	66.67%
Contract liability	$ 17.5	$ 10.2
Increase (decrease) in net contract liabilities	7.3
Revenue recognized	5.0
Unsatisfied performance obligation	$ 700.0
Minimum
Disaggregation of Revenue [Line Items]
Sales returns as percentage of gross sales, percent	1.00%
Unsatisfied performance obligation, period of recognition	3 years
Maximum
Disaggregation of Revenue [Line Items]
Sales returns as percentage of gross sales, percent	2.00%
Unsatisfied performance obligation, period of recognition	4 years

Business Acquisitions - Narrative (Details) - USD ($)		1 Months Ended	3 Months Ended
Business Acquisitions - Narrative (Details) - USD ($)	Feb. 02, 2018	Feb. 28, 2018	Mar. 31, 2018	Jan. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill			$ 1,760,100,000		$ 1,089,000,000
Line of Credit \| Term Loan Agreement
Business Acquisition [Line Items]
Line of credit, maximum borrowing capacity	$ 500,000,000			$ 500,000,000
Senior Notes \| Notes 2028 Term
Business Acquisition [Line Items]
Interest rate, stated percentage	3.50%	3.50%	3.50%
Face amount	$ 450,000,000	$ 450,000,000
Aclara
Business Acquisition [Line Items]
Consideration transferred to acquire business	1,100,000,000	$ 1,100,000,000
Goodwill	$ 669,000,000
Net sales			$ 90,400,000
Operating loss of acquiree since acquisition			$ 4,900,000

Business Acquisitions - Summary of Preliminary Estimate of the Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions		3 Months Ended
	Feb. 02, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill		$ 1,760.1		$ 1,089.0
Total Estimate of Consideration Transferred, Net of Cash Acquired		1,119.4	$ 19.2
Aclara
Business Acquisition [Line Items]
Accounts receivable	$ 116.1
Inventories	76.9
Other current assets	11.7
Property, plant and equipment	31.5
Intangible assets	444.0	$ 444.0
Accounts payable	(50.5)
Other accrued liabilities	(67.5)
Deferred tax liabilities	(72.3)
Other non-current liabilities	(37.0)
Noncontrolling interest	(2.5)
Goodwill	669.0
Total Estimate of Consideration Transferred, Net of Cash Acquired	$ 1,119.4

Business Acquisitions - Schedule of Preliminary Purchase Price Allocation to Identified Intangible Assets Acquired (Details) - Aclara - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Feb. 02, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value	$ 444.0	$ 444.0
Patents, tradenames and trademarks
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value	$ 55.0
Weighted Average Estimated Useful Life	20 years
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value	$ 204.0
Weighted Average Estimated Useful Life	17 years
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value	$ 185.0
Weighted Average Estimated Useful Life	13 years

Business Acquisitions - Pro-forma Nonrecurring Adjustments (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net income (loss)	$ 58.3	$ 62.8
Diluted (USD per share)	$ 1.05	$ 1.13
Acquisition-related costs, current period
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net income (loss)	$ 10.3	$ (10.3)
Diluted (USD per share)	$ 0.15	$ (0.14)
Acquisition-related costs, prior period
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net income (loss)	$ 0.0	$ (7.1)
Diluted (USD per share)	$ 0.00	$ (0.11)
Intangible amortization and inventory step up
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net income (loss)	$ 1.6	$ (16.9)
Diluted (USD per share)	$ 0.02	$ (0.19)
Interest expense
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net income (loss)	$ (2.1)	$ (7.2)
Diluted (USD per share)	$ (0.03)	$ (0.08)

Business Acquisitions - Summary of Pro Forma Information (Details) - Aclara - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Business Acquisition [Line Items]
Net sales	$ 1,037.9	$ 959.2
Net income attributable to Hubbell	$ 67.7	$ 39.5
Earnings Per Share:
Basic (USD per share)	$ 1.23	$ 0.71
Diluted (USD per share)	$ 1.22	$ 0.71

Segment Information (Details) $ in Millions	3 Months Ended
Segment Information (Details) $ in Millions	Mar. 31, 2018 USD ($) group	Mar. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Net sales	$ 991.2	$ 852.3
Operating Income	$ 99.6	$ 107.8
Operating Income as a % of Net Sales	10.00%	12.60%
Electrical
Segment Reporting Information [Line Items]
Number of business groups (in groups) \| group	3
Net sales	$ 618.1	$ 587.5
Operating Income	$ 61.2	$ 52.8
Operating Income as a % of Net Sales	9.90%	9.00%
Power
Segment Reporting Information [Line Items]
Net sales	$ 373.1	$ 264.8
Operating Income	$ 38.4	$ 55.0
Operating Income as a % of Net Sales	10.30%	20.80%

Inventories, net (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Inventory, Net, Items Net of Reserve Alternative [Abstract]
Raw material	$ 245.0	$ 190.0
Work-in-process	117.9	115.8
Finished goods	412.7	390.5
Inventory, gross	775.6	696.3
Excess of FIFO over LIFO cost basis	(61.3)	(61.6)
TOTAL	$ 714.3	$ 634.7

Goodwill and Intangible Assets, net - Changes in Goodwill (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Goodwill [Roll Forward]
BALANCE DECEMBER 31, 2017	$ 1,089.0
Current year acquisitions (Note 3 – Business Acquisitions)	669.0
Foreign currency translation and prior year acquisitions	2.1
BALANCE MARCH 31, 2018	1,760.1
Electrical
Goodwill [Roll Forward]
BALANCE DECEMBER 31, 2017	717.6
Current year acquisitions (Note 3 – Business Acquisitions)	0.0
Foreign currency translation and prior year acquisitions	1.9
BALANCE MARCH 31, 2018	719.5
Power
Goodwill [Roll Forward]
BALANCE DECEMBER 31, 2017	371.4
Current year acquisitions (Note 3 – Business Acquisitions)	669.0
Foreign currency translation and prior year acquisitions	0.2
BALANCE MARCH 31, 2018	$ 1,040.6

Goodwill and Intangible Assets, net - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) acquisition	Mar. 31, 2017 USD ($)
Goodwill [Line Items]
Number of acquisitions \| acquisition	1
Goodwill	$ 669.0
Amortization expense	15.4	$ 8.5
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remainder of 2018	56.7
2019	77.8
2020	76.2
2021	74.5
2022	66.1
2023	59.5
Aclara
Goodwill [Line Items]
Goodwill	$ 669.0

Goodwill and Intangible Assets, net - Other Intangible Assets (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Other Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 1,057.0	$ 613.4
Accumulated Amortization	(221.4)	(206.8)
Total intangible assets	1,110.9	667.2
Tradenames and other
Other Intangible Assets [Line Items]
Indefinite-lived intangible assets (excluding goodwill)	53.9	53.8
Patents, tradenames and trademarks
Other Intangible Assets [Line Items]
Finite-lived intangible assets, gross	206.5	151.4
Accumulated Amortization	(52.2)	(50.1)
Customer/agent relationships and other
Other Intangible Assets [Line Items]
Finite-lived intangible assets, gross	850.5	462.0
Accumulated Amortization	$ (169.2)	$ (156.7)

Other Accrued Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Accrued Liabilities [Abstract]
Customer program incentives	$ 27.0	$ 41.2
Accrued income taxes	29.8	27.5
Contract liabilities - deferred revenue	17.5	10.2
Customer refund liability	17.5	0.0
Accrued warranties	30.4	14.0
Other	88.7	82.0
TOTAL	$ 210.9	$ 174.9

Other Non-Current Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Liabilities, Other than Long-term Debt, Noncurrent [Abstract]
Pensions	$ 212.7	$ 213.2
Other post-retirement benefits	24.6	24.6
Deferred tax liabilities	95.3	23.7
Accrued warranties long-term	26.7	0.0
Other	135.9	118.0
TOTAL	$ 495.2	$ 379.5

Total Equity Total Equity - Composition of Equity (Details) - USD ($) $ / shares in Units, $ in Millions	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Stockholders' Equity Note [Abstract]
Common Stock – authorized 200.0 shares; issued and outstanding 54.8 and 54.9 shares	$ 0.6	$ 0.6
Additional paid-in capital	10.2	11.0
Retained earnings	1,908.9	1,892.4
Accumulated other comprehensive loss:
Pension and post retirement benefit plan adjustment, net of tax	(174.5)	(176.5)
Cumulative translation adjustment	(82.1)	(91.9)
Unrealized gain (loss) on investment, net of tax	(0.9)	(0.6)
Cash flow hedge gain (loss), net of tax	(0.2)	(0.8)
Total Accumulated other comprehensive loss	(257.7)	(269.8)
Hubbell shareholders’ equity	1,662.0	1,634.2
Noncontrolling interest	16.5	13.7
Total Equity	$ 1,678.5	$ 1,647.9	$ 1,588.8	$ 1,603.2
Common stock par value per share (USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	200,000,000.0	200,000,000.0
Common stock, shares, issued (in shares)	54,800,000	54,900,000
Common stock, shares, outstanding (in shares)	54,800,000	54,900,000

Total Equity Total Equity - Changes in Equity (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	$ 1,647.9	$ 1,603.2
Total comprehensive income	71.9	77.4
Stock-based compensation	5.1	4.2
ASC 606 adoption to retained earnings	0.6	0.0
Repurchase/surrender of shares of common stock	(6.1)	(55.9)
Issuance of shares related to directors’ deferred compensation, net	0.1	0.1
Dividends to noncontrolling interest	(1.1)	(1.4)
Aclara noncontrolling interest	2.4	0.0
Cash dividends declared	(42.3)	(38.8)
Ending equity	1,678.5	1,588.8
Hubbell Shareholders’ Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	1,634.2	1,592.8
Total comprehensive income	70.4	76.3
Stock-based compensation	5.1	4.2
ASC 606 adoption to retained earnings	0.6
Repurchase/surrender of shares of common stock	(6.1)	(55.9)
Issuance of shares related to directors’ deferred compensation, net	0.1	0.1
Cash dividends declared	(42.3)	(38.8)
Ending equity	1,662.0	1,578.7
Noncontrolling interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	13.7	10.4
Total comprehensive income	1.5	1.1
Dividends to noncontrolling interest	(1.1)	(1.4)
Aclara noncontrolling interest	2.4
Ending equity	$ 16.5	$ 10.1

Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	$ 1,647.9	$ 1,603.2
Other comprehensive income (loss) before reclassifications	9.9
Amounts reclassified from accumulated other comprehensive loss	2.2
Current period other comprehensive income (loss)	12.1
Ending equity	1,678.5	$ 1,588.8
Cash flow hedge (loss) gain
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	(0.8)
Other comprehensive income (loss) before reclassifications	0.4
Amounts reclassified from accumulated other comprehensive loss	0.2
Current period other comprehensive income (loss)	0.6
Ending equity	(0.2)
Unrealized gain (loss) on available-for- sale securities
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	(0.6)
Other comprehensive income (loss) before reclassifications	(0.3)
Amounts reclassified from accumulated other comprehensive loss	0.0
Current period other comprehensive income (loss)	(0.3)
Ending equity	(0.9)
Pension and post retirement benefit plan adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	(176.5)
Other comprehensive income (loss) before reclassifications	0.0
Amounts reclassified from accumulated other comprehensive loss	2.0
Current period other comprehensive income (loss)	2.0
Ending equity	(174.5)
Cumulative translation adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	(91.9)
Other comprehensive income (loss) before reclassifications	9.8
Amounts reclassified from accumulated other comprehensive loss	0.0
Current period other comprehensive income (loss)	9.8
Ending equity	(82.1)
AOCI Including Portion Attributable to Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	(269.8)
Ending equity	$ (257.7)

Accumulated Other Comprehensive Loss - Reclassifications (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax [Abstract]
Net sales	$ 991.2	$ 852.3
Cost of goods sold	(708.3)	(589.7)
Income before income taxes	75.8	90.9
Tax benefit (expense)	(16.0)	(27.0)
Gain (loss) net of tax	(2.2)
Cash flow hedge (loss) gain
Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax [Abstract]
Gain (loss) net of tax	(0.2)
Cash flow hedge (loss) gain \| Reclassification out of Accumulated Other Comprehensive Income
Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax [Abstract]
Cost of goods sold		(0.1)
Prior-service costs
Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax [Abstract]
Amortization of defined benefit pension and post retirement benefit items	0.2	0.2
Actuarial gains/(losses)
Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax [Abstract]
Amortization of defined benefit pension and post retirement benefit items	(2.8)	(2.8)
Amortization of defined benefit pension and post retirement benefit items
Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax [Abstract]
Amortization of defined benefit pension and post retirement benefit items	(2.6)	(2.6)
Tax benefit (expense)	0.6	0.9
Gain (loss) net of tax	(2.0)	(1.7)
AOCI Attributable to Parent
Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax [Abstract]
Gain (loss) net of tax	(2.2)	(1.8)
Forward Contracts \| Cash flow hedge (loss) gain \| Reclassification out of Accumulated Other Comprehensive Income
Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax [Abstract]
Net sales	0.0	0.0
Cost of goods sold	(0.2)
Income before income taxes	(0.2)	(0.1)
Tax benefit (expense)	0.0	0.0
Gain (loss) net of tax	$ (0.2)	$ (0.1)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Numerator:
Net income attributable to Hubbell	$ 58.3	$ 62.8
Less: Earnings allocated to participating securities	(0.2)	(0.2)
Net income available to common shareholders	$ 58.1	$ 62.6
Denominator [Abstract]
Average number of common shares outstanding (in shares)	54.7	55.2
Potential dilutive common shares (in shares)	0.4	0.4
Average number of diluted shares outstanding (in shares)	55.1	55.6
Basic (USD per share)	$ 1.06	$ 1.13
Diluted (USD per share)	$ 1.05	$ 1.13

Pension and Other Benefits (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1.1	$ 1.5
Interest cost	8.6	9.2
Expected return on plan assets	(8.5)	(8.5)
Amortization of prior service cost	0.0	0.0
Amortization of actuarial losses	2.8	2.8
NET PERIODIC BENEFIT COST	4.0	5.0
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.0	0.0
Interest cost	0.2	0.3
Expected return on plan assets	0.0	0.0
Amortization of prior service cost	(0.2)	(0.2)
Amortization of actuarial losses	0.0	0.0
NET PERIODIC BENEFIT COST	$ 0.0	$ 0.1

Pension and Other Benefits - Narrative (Details) - Foreign Plan $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan estimated total employer contributions in current fiscal year	$ 1.9
Contributions by employer	$ 0.5

Guarantees (Details) - USD ($)
$ in Millions

3 Months Ended

Mar. 31, 2018

Mar. 31, 2017

Movement in Standard Product Warranty Accrual [Roll Forward]

BALANCE AT JANUARY 1,

$ 14.0

$ 13.8

Provision

^[1]

3.2

2.7

Expenditures/other

(4.5)

2.1

Acquisitions

^[2]

44.4

0.0

BALANCE AT MARCH 31,

$ 57.1

$ 14.4

[1]	Refer to Note 7 – Other Accrued Liabilities and Note 8 – Other Non-Current Liabilities for a breakout of short-term and long-term warranties.
[2]	The acquisition amount disclosed relates to the Aclara acquisition. Refer to Note 3 – Business Acquisitions for additional information.

Fair Value Measurement - Narrative (Details) $ in Millions	3 Months Ended
Fair Value Measurement - Narrative (Details) $ in Millions	Mar. 31, 2018 USD ($) contract	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale investments	$ 57.1		$ 58.4
Trading securities	14.9		13.8
Purchase of trading securities related to deferred compensation plans	1.6	$ 1.6
Proceeds from securities sold	$ 0.4	$ 0.3
Number of foreign exchange contracts held (in contracts) \| contract	43
Long-term debt, fair value	$ 1,920.6		1,013.2
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale investments	0.0		0.0
Trading securities	14.9		$ 13.8
Forward exchange contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, notional amount	$ 37.0

Fair Value Measurement - Financial Assets and Liabilities by Hierarchy Level (Details) - USD ($)
$ in Millions

Mar. 31, 2018

Dec. 31, 2017

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Money market funds

^[1]

$ 55.8

$ 126.9

Available for sale investments

57.1

58.4

Trading securities

14.9

13.8

Deferred compensation plan liabilities

(14.9)

(13.8)

Derivatives:

Forward exchange contracts-Assets

^[2]

0.5

0.2

Forward exchange contracts-(Liabilities)

^[3]

(0.3)

(0.7)

TOTAL

113.1

184.8

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

^[1]

55.8

126.9

Available for sale investments

0.0

Trading securities

14.9

13.8

Deferred compensation plan liabilities

(14.9)

(13.8)

Derivatives:

Forward exchange contracts-Assets

^[2]

0.0

Forward exchange contracts-(Liabilities)

^[3]

0.0

TOTAL

55.8

126.9

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

^[1]

0.0

Available for sale investments

53.0

54.3

Trading securities

0.0

Deferred compensation plan liabilities

0.0

Derivatives:

Forward exchange contracts-Assets

^[2]

0.5

0.2

Forward exchange contracts-(Liabilities)

^[3]

(0.3)

(0.7)

TOTAL

53.2

53.8

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

^[1]

0.0

Available for sale investments

4.1

Trading securities

0.0

Deferred compensation plan liabilities

0.0

Derivatives:

Forward exchange contracts-Assets

^[2]

0.0

Forward exchange contracts-(Liabilities)

^[3]

0.0

TOTAL

$ 4.1

[1]	Money market funds are reflected in Cash and cash equivalents in the Condensed Consolidated Balance Sheet.
[2]	Forward exchange contracts-Assets are reflected in Other current assets in the Condensed Consolidated Balance Sheet.
[3]	Forward exchange contracts-(Liabilities) are reflected in Other accrued liabilities in the Condensed Consolidated Balance Sheet.

Fair Value Measurement - Cash Flow Hedging Relationships (Details) - Forward exchange contract - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Gain/(Loss) Recognized in Accumulated Other Comprehensive Income (net of tax)	$ 0.4	$ (0.2)
Net sales
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain/(Loss) Reclassified into Earnings Effective Portion (net of tax)	0.0	0.0
Cost of goods sold
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain/(Loss) Reclassified into Earnings Effective Portion (net of tax)	$ (0.2)	$ (0.1)

Restructuring Costs and Other - By Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 0.7	$ 5.5
Cost of goods sold
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.8	4.2
Selling & administrative expense
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(0.1)	1.3
Electrical Segment
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.7	4.7
Electrical Segment \| Cost of goods sold
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.8	3.7
Electrical Segment \| Selling & administrative expense
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(0.1)	1.0
Power Segment
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.0	0.8
Power Segment \| Cost of goods sold
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.0	0.5
Power Segment \| Selling & administrative expense
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 0.0	$ 0.3

Restructuring Costs and Other - Reserve (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Restructuring Reserve [Roll Forward]
Beginning Accrued Restructuring Balance 1/1/18	$ 20.9
Pre-tax Restructuring Costs	0.7	$ 5.5
Utilization and Foreign Exchange	(2.7)
Ending Accrued Restructuring Balance 3/31/2018	18.9
2018 Restructuring Actions
Restructuring Reserve [Roll Forward]
Beginning Accrued Restructuring Balance 1/1/18	0.0
Pre-tax Restructuring Costs	0.3
Utilization and Foreign Exchange	0.0
Ending Accrued Restructuring Balance 3/31/2018	0.3
2018 Restructuring Actions \| Severance
Restructuring Reserve [Roll Forward]
Beginning Accrued Restructuring Balance 1/1/18	0.0
Pre-tax Restructuring Costs	0.2
Utilization and Foreign Exchange	0.0
Ending Accrued Restructuring Balance 3/31/2018	0.2
2018 Restructuring Actions \| Asset write-downs
Restructuring Reserve [Roll Forward]
Beginning Accrued Restructuring Balance 1/1/18	0.0
Pre-tax Restructuring Costs	0.0
Utilization and Foreign Exchange	0.0
Ending Accrued Restructuring Balance 3/31/2018	0.0
2018 Restructuring Actions \| Facility closure and other costs
Restructuring Reserve [Roll Forward]
Beginning Accrued Restructuring Balance 1/1/18	0.0
Pre-tax Restructuring Costs	0.1
Utilization and Foreign Exchange	0.0
Ending Accrued Restructuring Balance 3/31/2018	0.1
2018 Restructuring Actions \| Withdrawal from Multiemployer Defined Benefit Plan
Restructuring Reserve [Roll Forward]
Pre-tax Restructuring Costs	12.5
2017 and Prior Restructuring Actions
Restructuring Reserve [Roll Forward]
Beginning Accrued Restructuring Balance 1/1/18	20.9
Pre-tax Restructuring Costs	0.4
Utilization and Foreign Exchange	(2.7)
Ending Accrued Restructuring Balance 3/31/2018	18.6
2017 and Prior Restructuring Actions \| Severance
Restructuring Reserve [Roll Forward]
Beginning Accrued Restructuring Balance 1/1/18	5.4
Pre-tax Restructuring Costs	(0.2)
Utilization and Foreign Exchange	(1.0)
Ending Accrued Restructuring Balance 3/31/2018	4.2
2017 and Prior Restructuring Actions \| Asset write-downs
Restructuring Reserve [Roll Forward]
Beginning Accrued Restructuring Balance 1/1/18	0.0
Pre-tax Restructuring Costs	0.0
Utilization and Foreign Exchange	0.0
Ending Accrued Restructuring Balance 3/31/2018	0.0
2017 and Prior Restructuring Actions \| Facility closure and other costs
Restructuring Reserve [Roll Forward]
Beginning Accrued Restructuring Balance 1/1/18	15.5
Pre-tax Restructuring Costs	0.6
Utilization and Foreign Exchange	(1.7)
Ending Accrued Restructuring Balance 3/31/2018	$ 14.4

Restructuring Costs and Other - Summary of Costs (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Total expected costs	$ 27.8
Costs incurred	0.7	$ 20.3
Remaining costs at 3/31/2018	6.8
2018 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Total expected costs	4.3
Costs incurred	0.3	0.0
Remaining costs at 3/31/2018	4.0
2018 Restructuring Actions \| Electrical Segment
Restructuring Cost and Reserve [Line Items]
Total expected costs	4.2
Costs incurred	0.2	0.0
Remaining costs at 3/31/2018	4.0
2018 Restructuring Actions \| Power Segment
Restructuring Cost and Reserve [Line Items]
Total expected costs	0.1
Costs incurred	0.1	0.0
Remaining costs at 3/31/2018	0.0
2017 and Prior Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Total expected costs	23.5
Costs incurred	0.4	20.3
Remaining costs at 3/31/2018	2.8
2017 and Prior Restructuring Actions \| Electrical Segment
Restructuring Cost and Reserve [Line Items]
Total expected costs	19.7
Costs incurred	0.5	16.9
Remaining costs at 3/31/2018	2.3
2017 and Prior Restructuring Actions \| Power Segment
Restructuring Cost and Reserve [Line Items]
Total expected costs	3.8
Costs incurred	(0.1)	$ 3.4
Remaining costs at 3/31/2018	$ 0.5

Long Term Debt and Financing Arrangements Long Term Debt and Financing Arrangements - Schedule of Long Term Debt (Details) - USD ($) $ in Millions	Mar. 31, 2018	Feb. 28, 2018	Feb. 02, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-Term Debt	$ 1,903.2			$ 987.1
Senior Notes \| Senior notes at 3.625%
Debt Instrument [Line Items]
Interest rate, stated percentage	3.625%
Long-Term Debt	$ 298.0			297.9
Senior Notes \| Senior notes at 3.35%
Debt Instrument [Line Items]
Interest rate, stated percentage	3.35%
Long-Term Debt	$ 394.6			394.4
Senior Notes \| Senior notes at 3.15%
Debt Instrument [Line Items]
Interest rate, stated percentage	3.15%
Long-Term Debt	$ 294.9			294.8
Senior Notes \| Senior notes at 3.50%
Debt Instrument [Line Items]
Interest rate, stated percentage	3.50%	3.50%	3.50%
Long-Term Debt	$ 442.8			0.0
Senior Notes \| Term loan, net of current portion of $25 million
Debt Instrument [Line Items]
Current portion of long-term debt	25.0
Long-Term Debt	$ 472.9			$ 0.0

Long Term Debt and Financing Arrangements - Narrative (Details) - USD ($)	1 Months Ended		3 Months Ended
	Feb. 28, 2018	Jan. 31, 2018	Mar. 31, 2018	Mar. 31, 2017	Feb. 02, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt borrowings			$ 947,500,000	$ 0
Short-term debt and current portion of long-term debt			$ 177,500,000			$ 68,100,000
Senior Notes \| Notes 2028 Term
Debt Instrument [Line Items]
Face amount	$ 450,000,000				$ 450,000,000
Interest rate, stated percentage	3.50%		3.50%		3.50%
Long-term debt borrowings	$ 442,600,000
Line of Credit \| Term Loan Agreement
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%
Revolving Credit Facility \| Line of Credit \| Credit Agreement
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity		$ 750,000,000
Line of credit facility covenants maximum debt to capitalization percentage		65.00%
Debt term		5 years
Line of credit facility, accordion feature, higher borrowing capacity option		$ 1,250,000,000.000