EnerSys (ENS) 10-Q 7 Feb 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Dec. 31, 2017	Feb. 02, 2018
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Trading Symbol	ENS
Entity Registrant Name	EnerSys
Entity Central Index Key	1,289,308
Current Fiscal Year End Date	--03-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		41,910,079

Consolidated Condensed Balance

Consolidated Condensed Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 31, 2017
Current assets:
Cash and cash equivalents	$ 571,322	$ 500,329
Accounts receivable, net of allowance for doubtful accounts: December 31, 2017 - $13,032; March 31, 2017 - $12,662	494,934	486,646
Total	421,970	360,694
Prepaid and other current assets	73,588	71,246
Total current assets	1,561,814	1,418,915
Property, plant, and equipment, net	374,736	348,549
Goodwill	348,878	328,657
Other intangible assets, net	149,368	153,960
Deferred taxes	34,730	31,587
Other assets	12,476	11,361
Total assets	2,482,002	2,293,029
Current liabilities:
Short-term debt	16,842	18,359
Accounts payable	227,294	222,493
Accrued expenses	206,032	226,579
Total current liabilities	450,168	467,431
Long-term Debt, Excluding Current Maturities	689,021	587,609
Deferred taxes	39,670	45,923
Other liabilities	177,169	83,697
Total liabilities	1,356,028	1,184,660
Commitments and contingencies
Equity:
Preferred Stock, $0.01 par value, 1,000,000 shares authorized, no shares issued or outstanding at December 31, 2017 and at March 31, 2017	0	0
Common Stock, $0.01 par value per share, 135,000,000 shares authorized; 54,590,184 shares issued and 42,126,817 shares outstanding at December 31, 2017; 54,370,810 shares issued and 43,447,536 shares outstanding at March 31, 2017	546	544
Additional paid-in capital	452,248	464,092
Treasury stock, at cost, 12,463,367 shares held as of December 31, 2017; 10,923,274 shares held as of March 31, 2017	(540,991)	(439,800)
Retained earnings	1,274,038	1,231,444
Accumulated other comprehensive income	(65,017)	(152,824)
Total EnerSys stockholders' equity	1,120,824	1,103,456
Noncontrolling interests	5,150	4,913
Total equity	1,125,974	1,108,369
Total liabilities and equity	$ 2,482,002	$ 2,293,029

Consolidated Condensed Balance3

Consolidated Condensed Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 31, 2017
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 13,032	$ 12,662
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	135,000,000	135,000,000
Common stock, shares issued (in shares)	54,590,184	54,370,810
Common stock, shares outstanding (in shares)	42,126,817	43,447,536
Treasury stock (in shares)	12,463,367	10,923,274

Consolidated Condensed Statemen

Consolidated Condensed Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Dec. 31, 2017	Jan. 01, 2017
Income Statement [Abstract]
Net sales	$ 658,935	$ 563,697	$ 1,898,849	$ 1,740,348
Cost of goods sold	491,970	408,315	1,408,913	1,254,678
Inventory adjustment relating to exit activities	0	(502)	0	2,157
Gross profit	166,965	155,884	489,936	483,513
Operating expenses	96,717	85,014	283,478	277,512
Restructuring charges and other exit charges (credits)	1,808	(1,153)	4,417	5,037
Legal proceedings charge	0	17,000	0	17,000
Operating earnings	68,440	55,023	202,041	183,964
Interest expense	6,469	5,646	18,712	16,820
Other (income) expense, net	(557)	(1,247)	4,736	(496)
Earnings before income taxes	62,528	50,624	178,593	167,640
Income tax expense	88,307	13,529	112,899	43,133
Net (loss) earnings	(25,779)	37,095	65,694	124,507
Net earnings attributable to noncontrolling interests	68	860	118	(1,937)
Net (loss) earnings attributable to EnerSys stockholders	$ (25,847)	$ 36,235	$ 65,576	$ 126,444
Net (loss) earnings per common share attributable to EnerSys stockholders:
Basic earnings (loss) per common share attributable to EnerSys stockholders (in dollars per share)	$ (0.61)	$ 0.83	$ 1.53	$ 2.92
Diluted earnings (loss) per common share attributable to EnerSys stockholders (in dollars per share)	(0.61)	0.82	1.51	2.88
Dividends per common share (in dollars per share)	$ 0.175	$ 0.175	$ 0.525	$ 0.525
Weighted average shares of common stock outstanding:
Basic weighted-average number of common shares outstanding (in shares)	42,125,745	43,429,525	42,837,986	43,375,474
Diluted weighted-average number of common shares outstanding (in shares)	42,125,745	44,049,674	43,345,926	43,943,010

Consolidated Condensed Stateme5

Consolidated Condensed Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Dec. 31, 2017	Jan. 01, 2017
Statement of Comprehensive Income [Abstract]
Net (loss) earnings	$ (25,779)	$ 37,095	$ 65,694	$ 124,507
Other comprehensive (loss) income:
Net unrealized (loss) gain on derivative instruments, net of tax	(587)	(2,017)	29	411
Pension funded status adjustment, net of tax	331	198	996	747
Foreign currency translation adjustment	14,053	(52,754)	86,901	(74,922)
Total other comprehensive gain (loss), net of tax	13,797	(54,573)	87,926	(73,764)
Total comprehensive (loss) income	(11,982)	(17,478)	153,620	50,743
Comprehensive income (loss) attributable to noncontrolling interests	156	648	237	(2,343)
Comprehensive (loss) income attributable to EnerSys stockholders	$ (12,138)	$ (18,126)	$ 153,383	$ 53,086

Consolidated Condensed Stateme6

Consolidated Condensed Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Dec. 31, 2017	Jan. 01, 2017
Cash flows from operating activities
Net (loss) earnings	$ 65,694	$ 124,507
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	40,320	40,468
Write-off of assets relating to restructuring charges	210	1,435
Non-cash write-off of property, plant and equipment	0	6,300
Derivatives not designated in hedging relationships:
Net (gains) losses	(105)	202
Cash settlements	(234)	(646)
Provision for doubtful accounts	775	1,952
Deferred income taxes	(7,228)	(683)
Non-cash interest expense	1,289	1,041
Stock-based compensation	14,773	14,556
Loss (gain) on disposal of property, plant, and equipment	69	(10)
Legal proceedings accrual	0	17,000
Changes in assets and liabilities, net of effects of acquisitions:
Accounts receivable	12,987	22,843
Inventories	(44,389)	(55,888)
Prepaid and other current assets	(1,241)	(11,545)
Other assets	(1,142)	857
Accounts payable	(10,619)	(14,701)
Accrued expenses	(30,485)	13,856
Other liabilities	89,228	5,163
Net cash provided by operating activities	129,902	166,707
Cash flows from investing activities
Capital expenditures	(43,086)	(36,008)
Purchase of businesses	(2,964)	(12,392)
Proceeds from disposal of property, plant, and equipment	395	568
Net cash used in investing activities	(45,655)	(47,832)
Cash flows from financing activities
Net (payments) borrowings on short-term debt	(1,376)	13,639
Proceeds from 2017 Term Loan	150,000	0
Repayments of 2011 Term Loan	(127,500)	(11,250)
Debt issuance costs	(2,677)	0
Option proceeds	758	5
Payment of taxes related to net share settlement of equity awards	(7,477)	(7,668)
Purchase of treasury stock	(121,191)	0
Dividends paid to stockholders	(22,339)	(22,800)
Other	(19)	(77)
Net cash used in financing activities	(51,521)	(23,601)
Effect of exchange rate changes on cash and cash equivalents	38,267	(25,432)
Net increase in cash and cash equivalents	70,993	69,842
Cash and cash equivalents at beginning of period	500,329	397,307
Cash and cash equivalents at end of period	571,322	467,149
2017 Credit Facility, due 2022
Cash flows from financing activities
Proceeds from 2011 Revolver borrowings	356,750	0
Repayments of 2011 Revolver borrowings	(111,450)	0
2011 Credit Facility, due 2018
Cash flows from financing activities
Proceeds from 2011 Revolver borrowings	147,050	191,300
Repayments of 2011 Revolver borrowings	$ (312,050)	$ (186,750)

Basis of Presentation

Basis of Presentation	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated condensed financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information and with the instructions to 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included, unless otherwise disclosed. Operating results for the three and nine-month periods ended December 31, 2017 are not necessarily indicative of the results that may be expected for the fiscal year ending March 31, 2018. The consolidated condensed balance sheet at March 31, 2017 has been derived from the audited consolidated financial statements at that date but does not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. The financial statements should be read in conjunction with the Consolidated Financial Statements and Notes thereto included in the Company’s 2017 Annual Report on Form 10-K (SEC File No. 001-32253), which was filed on May 30, 2017 (the “ 2017 Annual Report ”). The Company reports interim financial information for 13-week periods, except for the first quarter, which always begins on April 1, and the fourth quarter, which always ends on March 31. The four quarters in fiscal 2018 end on July 2, 2017, October 1, 2017, December 31, 2017, and March 31, 2018, respectively. The four quarters in fiscal 2017 ended on July 3, 2016, October 2, 2016, January 1, 2017, and March 31, 2017, respectively. The consolidated condensed financial statements include the accounts of the Company and its wholly-owned subsidiaries and any partially owned subsidiaries that the Company has the ability to control. All intercompany transactions and balances have been eliminated in consolidation. Recently Issued Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606)” providing guidance on revenue from contracts with customers that will supersede most current revenue recognition guidance, including industry-specific guidance. The underlying principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. In July 2015, the FASB voted to delay the effective date for interim and annual reporting periods beginning after December 15, 2017, with early adoption permissible one year earlier. The standard permits the use of either modified retrospective or full retrospective transition methods. The Company has substantially completed an impact assessment of the potential changes from adopting ASU 2014-09. The impact assessment included a review of customer arrangements across all of its global business units and an in-depth analysis of its global revenue processes and accounting policies to identify potential areas where change may be needed to comply with this guidance. The Company plans to apply the modified retrospective transition method. The Company assembled an implementation work team to assess and document the accounting conclusions for the adoption of ASU 2014-09. Based on this analysis, the Company does not believe the adoption of the ASU will have a material impact to the consolidated financial statements. The Company continues to assess the potential impact on accounting policies, internal control processes and related disclosures required under the new guidance. In February 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842)”, which sets out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e. lessees and lessors). This update requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase of the leased asset by the lessee. This classification will determine whether the lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. The new standard requires lessors to account for leases using an approach that is substantially equivalent to existing guidance for sales-type leases, direct financing leases and operating leases. This update is effective for annual periods beginning after December 15, 2018, using a modified retrospective approach, with early adoption permitted. The Company is currently assessing the potential impact that the adoption will have on its consolidated financial statements. In October 2016, the FASB issued ASU No. 2016-16, “Income Taxes (Topic 740)”: Intra-Entity Transfers of Assets Other than Inventory. ASU 2016-16 requires that an entity recognize the income tax consequences of an intra-entity transfer of assets other than inventory when the transfer occurs. This update is effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within those annual reporting periods. The Company early adopted the standard on a modified retrospective basis during the first quarter of fiscal 2018 through a cumulative-effect adjustment directly to retained earnings of $137 , as of the beginning of the period of adoption. In March 2017, the FASB issued ASU No. 2017-07, “Compensation—Retirement Benefits (Topic 715)”, which requires an entity to report the service cost component of pension and other postretirement benefit costs in the same line item as other compensation costs. The other components of net (benefit) cost will be required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. This standard is effective for interim and annual reporting periods beginning after December 15, 2017, with early adoption permitted. The Company is currently assessing the potential impact that the adoption will have on its consolidated financial statements.

Inventories

Inventories	9 Months Ended
	Dec. 31, 2017
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories, net consist of: December 31, 2017 March 31, 2017 Raw materials $ 96,666 $ 85,604 Work-in-process 138,540 107,177 Finished goods 186,764 167,913 Total $ 421,970 $ 360,694

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments Recurring Fair Value Measurements The following tables represent the financial assets and (liabilities) measured at fair value on a recurring basis as of December 31, 2017 and March 31, 2017 , and the basis for that measurement: Total Fair Value Measurement December 31, 2017 Quoted Price in Significant Significant Lead forward contracts $ 47 $ — $ 47 $ — Foreign currency forward contracts (266 ) — (266 ) — Total derivatives $ (219 ) $ — $ (219 ) $ — Total Fair Value Measurement March 31, 2017 Quoted Price in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Lead forward contracts $ 1,163 $ — $ 1,163 $ — Foreign currency forward contracts (313 ) — (313 ) — Total derivatives $ 850 $ — $ 850 $ — The fair values of lead forward contracts are calculated using observable prices for lead as quoted on the London Metal Exchange (“LME”) and, therefore, were classified as Level 2 within the fair value hierarchy, as described in Note 1, Summary of Significant Accounting Policies to the Company's consolidated financial statements included in its 2017 Annual Report . The fair values for foreign currency forward contracts are based upon current quoted market prices and are classified as Level 2 based on the nature of the underlying market in which these derivatives are traded. Financial Instruments The fair values of the Company’s cash and cash equivalents approximate carrying value due to their short maturities. The fair value of the Company’s short-term debt and borrowings under the new 2017 Credit Facility and the previous 2011 Credit Facility (each as defined in Note 9), approximate their respective carrying value, as they are variable rate debt and the terms are comparable to market terms as of the balance sheet dates and are classified as Level 2. The Company's 5.00% Senior Notes due 2023 (the “Notes”), with an original face value of $300,000 , were issued in April 2015. The fair value of these Notes represent the trading values based upon quoted market prices and are classified as Level 2. The Notes were trading at approximately 104% and 101% of face value on December 31, 2017 and March 31, 2017 , respectively. The carrying amounts and estimated fair values of the Company’s derivatives and Notes at December 31, 2017 and March 31, 2017 were as follows: December 31, 2017 March 31, 2017 Carrying Fair Value Carrying Fair Value Financial assets: Derivatives (1) $ 47 $ 47 $ 1,163 $ 1,163 Financial liabilities: Notes (2) $ 300,000 $ 313,500 $ 300,000 $ 303,000 Derivatives (1) 266 266 313 313 (1) Represents lead and foreign currency forward contracts (see Note 4 for asset and liability positions of the lead and foreign currency forward contracts at December 31, 2017 and March 31, 2017 ). (2) The fair value amount of the Notes at December 31, 2017 and March 31, 2017

Derivative Financial Instrument

Derivative Financial Instruments	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments The Company utilizes derivative instruments to reduce its exposure to fluctuations in commodity prices and foreign exchange rates under established procedures and controls. The Company does not enter into derivative contracts for speculative purposes. The Company’s agreements are with creditworthy financial institutions and the Company anticipates performance by counterparties to these contracts and therefore no material loss is expected. Derivatives in Cash Flow Hedging Relationships Lead Forward Contracts The Company enters into lead forward contracts to fix the price for a portion of its lead purchases. Management considers the lead forward contracts to be effective against changes in the cash flows of the underlying lead purchases. The vast majority of such contracts are for a period not extending beyond one year. At December 31, 2017 and March 31, 2017 , the Company has hedged the price to purchase approximately 54.0 million pounds and 45.0 million pounds of lead, respectively, for a total purchase price of $60,849 and $46,550 , respectively. Foreign Currency Forward Contracts The Company uses foreign currency forward contracts and options to hedge a portion of the Company’s foreign currency exposures for lead, as well as other foreign currency exposures so that gains and losses on these contracts offset changes in the underlying foreign currency denominated exposures. The vast majority of such contracts are for a period not extending beyond one year. As of December 31, 2017 and March 31, 2017 , the Company had entered into a total of $52,801 and $30,751 , respectively, of such contracts. In the coming twelve months, the Company anticipates that $3,133 of pretax gain relating to lead and foreign currency forward contracts will be reclassified from accumulated other comprehensive income (“AOCI”) as part of cost of goods sold. This amount represents the current net unrealized impact of hedging lead and foreign exchange rates, which will change as market rates change in the future, and will ultimately be realized in the Consolidated Condensed Statements of Income as an offset to the corresponding actual changes in lead costs to be realized in connection with the variable lead cost and foreign exchange rates being hedged. Derivatives not Designated in Hedging Relationships Foreign Currency Forward Contracts The Company also enters into foreign currency forward contracts to economically hedge foreign currency fluctuations on intercompany loans and foreign currency denominated receivables and payables. These are not designated as hedging instruments and changes in fair value of these instruments are recorded directly in the Consolidated Condensed Statements of Income. As of December 31, 2017 and March 31, 2017 , the notional amount of these contracts was $24,132 and $13,560 , respectively. Presented below in tabular form is information on the location and amounts of derivative fair values in the Consolidated Condensed Balance Sheets and derivative gains and losses in the Consolidated Condensed Statements of Income: Fair Value of Derivative Instruments December 31, 2017 and March 31, 2017 Derivatives and Hedging Activities Designated as Cash Flow Hedges Derivatives and Hedging Activities Not Designated as Hedging Instruments December 31, 2017 March 31, 2017 December 31, 2017 March 31, 2017 Prepaid and other current assets Lead forward contracts $ 47 $ 1,163 $ — $ — Foreign currency forward contracts — 11 14 — Total assets $ 47 $ 1,174 $ 14 $ — Accrued expenses Foreign currency forward contracts $ 280 $ — $ — $ 324 Total liabilities $ 280 $ — $ — $ 324 The Effect of Derivative Instruments on the Consolidated Condensed Statements of Income For the quarter ended December 31, 2017 Derivatives Designated as Cash Flow Hedges Pretax Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion) Location of Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Pretax Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Lead forward contracts $ (396 ) Cost of goods sold $ 2,266 Foreign currency forward contracts (87 ) Cost of goods sold (1,811 ) Total $ (483 ) $ 455 Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivatives Pretax Gain (Loss) Foreign currency forward contracts Other (income) expense, net $ 93 Total $ 93 The Effect of Derivative Instruments on the Consolidated Condensed Statements of Income For the quarter ended January 1, 2017 Derivatives Designated as Cash Flow Hedges Pretax Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion) Location of Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Pretax Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Lead forward contracts $ (2,362 ) Cost of goods sold $ 1,524 Foreign currency forward contracts 595 Cost of goods sold (93 ) Total $ (1,767 ) $ 1,431 Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivatives Pretax Gain (Loss) Foreign currency forward contracts Other (income) expense, net $ (25 ) Total $ (25 ) The Effect of Derivative Instruments on the Consolidated Condensed Statements of Income For the nine months ended December 31, 2017 Derivatives Designated as Cash Flow Hedges Pretax Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion) Location of Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Pretax Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Lead forward contracts $ 2,686 Cost of goods sold $ 2,177 Foreign currency forward contracts (3,175 ) Cost of goods sold (2,714 ) Total $ (489 ) $ (537 ) Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivatives Pretax Gain (Loss) Foreign currency forward contracts Other (income) expense, net $ 105 Total $ 105 The Effect of Derivative Instruments on the Consolidated Condensed Statements of Income For the nine months ended January 1, 2017 Derivatives Designated as Cash Flow Hedges Pretax Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion) Location of Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Pretax Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Lead forward contracts $ 2,258 Cost of goods sold $ 2,800 Foreign currency forward contracts 873 Cost of goods sold (319 ) Total $ 3,131 $ 2,481 Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivatives Pretax Gain (Loss) Foreign currency forward contracts Other (income) expense, net $ (202 ) Total $ (202 )

Income Taxes

Income Taxes	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Income Taxes	Income Taxes The Company’s income tax provision consists of federal, state and foreign income taxes. The tax provision for the third quarters of fiscal 2018 and 2017 was based on the estimated effective tax rates applicable for the full years ending March 31, 2018 and March 31, 2017 , respectively, after giving effect to items specifically related to the interim periods. The Company’s effective income tax rate with respect to any period may be volatile based on the mix of income in the tax jurisdictions in which the Company operates, change in tax laws and the amount of the Company's consolidated income before taxes. On December 22, 2017, the Tax Cuts and Jobs Act (“Tax Act”) was enacted into law. Among the significant changes resulting from the law, the Tax Act reduces the U.S. federal income tax rate from 35% to 21% effective January 1, 2018, and requires companies to pay a one-time transition tax on unrepatriated cumulative non-U.S. earnings of foreign subsidiaries and creates new taxes on certain foreign sourced earnings. In accordance with ASC 740, “Income Taxes,” the Company is required to record the effects of tax law changes in the period enacted. The rate change is administratively effective at the beginning of the Company's fiscal year, using a blended rate for the annual period. As a result, the Company's blended U.S. statutory tax rate for fiscal 2018 is 31.5% . As of December 31, 2017, the Company has not completed its accounting for the tax effects of enactment of the Tax Act; however, in certain cases, as described below, the Company made a reasonable estimate of the effects on its existing deferred tax balances and the one-time transition tax. The Company's results for the three and nine months ended December 31, 2017, contain estimates of the impact of the Tax Act as permitted by Staff Accounting Bulletin 118 “SAB 118” issued by the Securities and Exchange Commission on December 22, 2017. These amounts are considered provisional and may be affected by future guidance if and when issued. As a result of the Tax Act, the third quarter fiscal 2018 financial statements include a provisional net tax expense of $77,347 which is comprised of the following: Foreign tax effects: The one-time transition tax is based on the Company's total post-1986 earnings and profits (E&P) that was previously deferred from U.S. income taxes. The Company recorded a provisional amount for a one-time transition tax liability for its foreign subsidiaries, resulting in an increase in income tax expense of $94,000 . The estimated transition tax of $94,000 is recorded under current income tax payable and non-current income tax payable, at $7,520 and $86,480 , respectively, and is payable over eight years. Further, the transition tax is based in part on the amount of those earnings held in cash and other specified assets. This amount may change when the Company finalizes both the calculation of post-1986 foreign E&P previously deferred from U.S. federal taxation and the amounts held in cash or other specified assets. No additional income taxes have been provided for any remaining undistributed foreign earnings not subject to the transition tax, or any additional outside basis difference inherent in these entities, as these amounts continue to be indefinitely reinvested in foreign operations. Deferred tax assets and liabilities: The Company remeasured certain deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future, which is generally 21%. However, the Company is still analyzing certain aspects of the Tax Act and refining its calculations, which could potentially affect the measurement of these balances or give rise to new deferred tax amounts. The provisional amount recorded, related to the remeasurement of the Company's deferred tax balance was a tax benefit of $14,706 . Finally, the Company recorded a provisional tax benefit of $1,947 related to the reduction of the fiscal 2018 federal tax rate to 31.5% . In all cases, the Company may adjust these provisional amounts which could potentially affect the measurement and impact on tax expense as the Company refines its calculations within a reasonable period not to exceed one year from the enactment date. The consolidated effective income tax rates for the third quarters of fiscal 2018 and 2017 were 141.2% and 26.7% , respectively, and for the nine months of fiscal 2018 and 2017 were 63.2% and 25.7% , respectively. The rate increase in the third quarter and nine months of fiscal 2018 compared to the comparable prior year periods of fiscal 2017 is primarily due to the impact of the Tax Act in the third quarter of fiscal 2018, offset by the German regulatory proceedings charge of $17,000 (with no associated tax benefit) recorded in the third quarter of fiscal 2017 and changes in the mix of earnings among tax jurisdictions. Foreign income as a percentage of worldwide income is estimated to be 64% for fiscal 2018 compared to 60% for fiscal 2017 . The foreign effective income tax rates for the nine months of fiscal 2018 and 2017 were 11.4% and 15.9% , respectively. The rate decrease compared to the prior year period is primarily due to the German regulatory proceedings charge of $17,000 (with no associated tax benefit) recorded in the third quarter of fiscal 2017 and changes in the mix of earnings among tax jurisdictions. Income from the Company's Swiss subsidiary comprised a substantial portion of the Company's overall foreign mix of income and is taxed at an effective income tax rate of approximately 6%

Warranty

Warranty	9 Months Ended
	Dec. 31, 2017
Disclosure Analysis Of Changes In Liability For Product Warranties [Abstract]
Warranty	Warranty The Company provides for estimated product warranty expenses when the related products are sold, with related liabilities included within accrued expenses and other liabilities. As warranty estimates are forecasts that are based on the best available information, primarily historical claims experience, claims costs may ultimately differ from amounts provided. An analysis of changes in the liability for product warranties is as follows: Quarter ended Nine months ended December 31, 2017 January 1, 2017 December 31, 2017 January 1, 2017 Balance at beginning of period $ 47,113 $ 48,112 $ 46,116 $ 48,422 Current period provisions 6,204 4,085 13,012 14,932 Costs incurred (3,843 ) (4,250 ) (10,880 ) (12,492 ) Foreign currency translation adjustment 23 (1,720 ) 1,249 (4,635 ) Balance at end of period $ 49,497 $ 46,227 $ 49,497 $ 46,227

Commitments, Contingencies and

Commitments, Contingencies and Litigation	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Commitments, Contingencies and Litigation	Commitments, Contingencies and Litigation Litigation and Other Legal Matters In the ordinary course of business, the Company and its subsidiaries are routinely defendants in or parties to pending and threatened legal actions and proceedings, including actions brought on behalf of various classes of claimants. These actions and proceedings are generally based on alleged violations of environmental, anticompetition, employment, contract and other laws. In some of these actions and proceedings, claims for substantial monetary damages are asserted against the Company and its subsidiaries. In the ordinary course of business, the Company and its subsidiaries are also subject to regulatory and governmental examinations, information gathering requests, inquiries, investigations, and threatened legal actions and proceedings. In connection with formal and informal inquiries by federal, state, local and foreign agencies, the Company and its subsidiaries receive numerous requests, subpoenas and orders for documents, testimony and information in connection with various aspects of their activities. European Competition Investigations Certain of the Company’s European subsidiaries had received subpoenas and requests for documents and, in some cases, interviews from, and have had on-site inspections conducted by, the competition authorities of Belgium, Germany and the Netherlands relating to conduct and anticompetitive practices of certain industrial battery participants. The Company settled the Belgian regulatory proceeding in February 2016 by acknowledging certain anticompetitive practices and conduct and agreeing to pay a fine of $1,962 , which was paid in March 2016. As of December 31, 2017 and March 31, 2017 , the Company had a reserve balance of $2,058 and $1,830 , respectively, relating to certain ancillary matters associated with the Belgian regulatory proceeding. The change in the reserve balance between December 31, 2017 and March 31, 2017 was solely due to foreign currency translation impact. In June 2017, the Company settled a portion of its previously disclosed proceeding involving the German competition authority relating to conduct involving the Company's motive power battery business and agreed to pay a fine of $14,811 , which was paid in July 2017. As of December 31, 2017 and March 31, 2017, the Company had a reserve balance of $0 and $ 13,463 , respectively, relating to this matter. Also in June 2017, the German competition authority issued a fining decision related to the Company's reserve power battery business, which constitutes the remaining portion of the previously disclosed German proceeding. The Company is appealing this decision, including payment of the proposed fine of $11,415 , and believes that the reserve power matter does not, based on current facts and circumstances known to management, require an accrual. The Company is not required to escrow any portion of this fine during the appeal process. In July 2017, the Company settled the Dutch regulatory proceeding and agreed to pay a fine of $11,229 , which was paid in August 2017. As of December 31, 2017 and March 31, 2017, the Company had a reserve balance of $0 and $10,258 , respectively, relating to the Dutch regulatory proceeding. As of December 31, 2017 and March 31, 2017 , the Company had a total reserve balance of $2,058 and $25,551 , respectively, in connection with these investigations and other related legal matters, included in accrued expenses on the Consolidated Condensed Balance Sheets. The foregoing estimate of losses is based upon currently available information for these proceedings. However, the precise scope, timing and time period at issue, as well as the final outcome of the investigations or customer claims, remain uncertain. Accordingly, the Company’s estimate may change from time to time, and actual losses could vary. Environmental Issues As a result of its operations, the Company is subject to various federal, state, and local, as well as international environmental laws and regulations and is exposed to the costs and risks of registering, handling, processing, storing, transporting, and disposing of hazardous substances, especially lead and acid. The Company’s operations are also subject to federal, state, local and international occupational safety and health regulations, including laws and regulations relating to exposure to lead in the workplace. The Company is responsible for certain cleanup obligations at the former Yuasa battery facility in Sumter, South Carolina, that predates its ownership of this facility. This manufacturing facility was closed in 2001 and the Company established a reserve for this facility, which was $1,117 and $1,123 as of December 31, 2017 and March 31, 2017 . Based on current information, the Company’s management believes this reserve is adequate to satisfy the Company’s environmental liabilities at this facility. This facility is separate from the Company’s current metal fabrication facility in Sumter. Lead and Foreign Currency Forward Contracts

Restructuring

Restructuring	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Restructuring	Restructuring Plans During fiscal 2016, the Company announced restructurings to improve efficiencies primarily related to its motive power assembly and distribution center in Italy and its sales and administration organizations in EMEA. In addition, the Company announced a further restructuring related to its manufacturing operations in Europe. The program was completed during the third quarter of fiscal 2018. Total charges for this program were $6,568 primarily for cash expenses of $6,161 for employee severance-related payments of approximately 130 employees and other charges of $407 . In fiscal 2016, the Company recorded restructuring charges of $5,232 and recorded an additional $1,251 during fiscal 2017. The Company incurred $2,993 in costs against the accrual in fiscal 2016 and incurred an additional $3,037 against the accrual during fiscal 2017. During the nine months of fiscal 2018 , the Company recorded restructuring charges of $85 and incurred $499 against the accrual. During fiscal 2017, the Company announced restructuring programs to improve efficiencies primarily related to its motive power production in EMEA. The Company estimates that the total charges for these actions will amount to approximately $4,700 , primarily from cash charges for employee severance-related payments and other charges. The Company estimates that these actions will result in the reduction of approximately 45 employees upon completion. During fiscal 2017, the Company recorded restructuring charges of $3,104 and incurred $749 in costs against the accrual. During the nine months of fiscal 2018 , the Company recorded restructuring charges of $1,610 and incurred $1,725 against the accrual. As of December 31, 2017 , the reserve balance associated with these actions is $2,406 . The Company does not expect to be committed to additional restructuring charges related to this action, which is expected to be completed in fiscal 2019. During the first quarter of fiscal 2017, the Company announced a restructuring primarily to complete the transfer of equipment and clean-up of its manufacturing facility located in Jiangdu, the People’s Republic of China, which stopped production during fiscal 2016. This program was completed during the first quarter of fiscal 2018. The total cash charges for these actions amounted to $779 . During fiscal 2017, the Company recorded charges of $779 and incurred $648 in costs against the accrual. During the nine months of fiscal 2018 , the Company recorded charges of $0 and incurred $129 in costs against the accrual. During fiscal 2018, the Company announced restructuring programs to improve efficiencies primarily related to supply chain and general operations in EMEA. The Company estimates that the total charges for these actions will amount to approximately $3,400 , primarily from cash charges for employee severance-related payments and other charges. The Company estimates that these actions will result in the reduction of approximately 50 employees upon completion. During the nine months of fiscal 2018, the Company recorded restructuring charges of $1,477 and incurred $1,069 in costs against the accrual. As of December 31, 2017 , the reserve balance associated with these actions is $406 . The Company expects to be committed to an additional $1,900 in restructuring charges related to this action, which it expects to complete in fiscal 2019. During the second quarter of fiscal 2018, the Company completed the sale of its Cleveland, Ohio facility and recorded a non-cash loss on the sale of the building of $210 and other cash charges of $75 . The Cleveland facility ceased charger production in fiscal 2017. During fiscal 2018, the Company announced a restructuring program to improve efficiencies of its general operations in the Americas. The Company estimates that the total charges for these actions will amount to approximately $1,000 , from cash charges for employee severance-related payments to approximately 60 salaried employees. During the nine months of fiscal 2018, the Company recorded restructuring charges of $960 and incurred $386 in costs against the accrual. As of December 31, 2017, the reserve balance associated with this action is $574 . The Company expects to complete this action in fiscal 2019. A roll-forward of the restructuring reserve is as follows: Employee Severance Other Total Balance as of March 31, 2017 $ 2,668 $ 144 $ 2,812 Accrued 3,890 317 4,207 Costs incurred (3,421 ) (462 ) (3,883 ) Foreign currency impact 249 1 250 Balance as of December 31, 2017 $ 3,386 $ — $ 3,386

Debt

Debt	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Debt	Debt The following summarizes the Company’s long-term debt as of December 31, 2017 and March 31, 2017 : December 31, 2017 March 31, 2017 Principal Unamortized Issuance Costs Principal Unamortized Issuance Costs 5.00% Senior Notes due 2023 $ 300,000 $ 3,278 $ 300,000 $ 3,746 2017 Credit Facility, due 2022 395,300 3,001 — — 2011 Credit Facility, due 2018 — — 292,500 1,145 $ 695,300 $ 6,279 $ 592,500 $ 4,891 Less: Unamortized issuance costs 6,279 4,891 Long-term debt, net of unamortized issuance costs $ 689,021 $ 587,609 5.00% Senior Notes The Company's $300,000 Notes bear interest at a rate of 5.00% per annum. Interest is payable semiannually in arrears on April 30 and October 30 of each year, commencing on October 30, 2015. The Notes will mature on April 30, 2023, unless earlier redeemed or repurchased in full. The Notes are unsecured and unsubordinated obligations of the Company. The Notes are fully and unconditionally guaranteed (the “Guarantees”), jointly and severally, by certain of its subsidiaries that are guarantors (the “Guarantors”) under the 2011 Credit Facility and its successor, the 2017 Credit Facility. The Guarantees are unsecured and unsubordinated obligations of the Guarantors. 2017 Credit Facility On August 4, 2017, the Company entered into a new credit facility (“2017 Credit Facility”). The 2017 Credit Facility matures on September 30, 2022 and comprises a $600,000 senior secured revolving credit facility (“2017 Revolver”) and a $150,000 senior secured term loan (“2017 Term Loan”). The Company's previous credit facility (“2011 Credit Facility”) comprised a $500,000 senior secured revolving credit facility (“2011 Revolver”) and a $150,000 senior secured incremental term loan (the “2011 Term Loan”) with a maturity date of September 30, 2018. On August 4, 2017, the outstanding balance on the 2011 Revolver and the 2011 Term Loan of $240,000 and $123,750 , respectively, was repaid utilizing borrowings from the 2017 Credit Facility. As of December 31, 2017 , the Company had $245,300 outstanding on the 2017 Revolver and $150,000 under the 2017 Term Loan. The quarterly installments payable on the 2017 Term Loan are $1,875 beginning December 31, 2018, $2,813 beginning December 31, 2019 and $3,750 beginning December 31, 2020 with a final payment of $105,000 on September 30, 2022. The 2017 Credit Facility may be increased by an aggregate amount of $325,000 in revolving commitments and/or one or more new tranches of term loans, under certain conditions. Both the 2017 Revolver and the 2017 Term Loan bear interest, at the Company's option, at a rate per annum equal to either (i) the London Interbank Offered Rate (“LIBOR”) plus between 1.25% and 2.00% (currently 1.25% and based on the Company's consolidated net leverage ratio) or (ii) the Base Rate (which equals, for any day a fluctuating rate per annum equal to the highest of (a) the Federal Funds Effective Rate plus 0.50% , (b) Bank of America “Prime Rate” and (c) the Eurocurrency Base Rate plus 1% ; provided that, if the Base Rate shall be less than zero, such rate shall be deemed zero). Obligations under the 2017 Credit Facility are secured by substantially all of the Company’s existing and future acquired assets, including substantially all of the capital stock of the Company’s United States subsidiaries that are guarantors under the 2017 Credit Facility and 65% of the capital stock of certain of the Company’s foreign subsidiaries that are owned by the Company’s United States subsidiaries. The current portion of the 2017 Term Loan of $1,875 is classified as long-term debt as the Company expects to refinance the future quarterly payments with revolver borrowings under its 2017 Credit Facility. Short-Term Debt As of December 31, 2017 and March 31, 2017 , the Company had $16,842 and $18,359 , respectively, of short-term borrowings. The weighted-average interest rate on these borrowings was approximately 8% and 7% at December 31, 2017 and March 31, 2017 , respectively. Letters of Credit As of December 31, 2017 and March 31, 2017 , the Company had $3,074 and $2,189 , respectively, of standby letters of credit. Debt Issuance Costs In connection with the refinancing, the Company incurred $2,677 in debt issuance costs and wrote off $301 relating to the 2011 Credit Facility. Amortization expense, relating to debt issuance costs, included in interest expense was $314 and $347 , respectively, for the quarters ended December 31, 2017 and January 1, 2017 and $988 and $1,041 , respectively, for the nine months ended December 31, 2017 and January 1, 2017 . Debt issuance costs, net of accumulated amortization, totaled $6,279 and $ 4,891 , respectively, at December 31, 2017 and March 31, 2017 . Available Lines of Credit As of December 31, 2017 and March 31, 2017 , the Company had available and undrawn, under all its lines of credit, $503,807 and $475,947 , respectively, including $150,832 and $142,872 , respectively, of uncommitted lines of credit as of December 31, 2017 and March 31, 2017

Retirement Plans

Retirement Plans	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Retirement Plans	Retirement Plans The following tables present the components of the Company’s net periodic benefit cost related to its defined benefit pension plans: United States Plans International Plans Quarter ended Quarter ended December 31, 2017 January 1, 2017 December 31, 2017 January 1, 2017 Service cost $ — $ 96 $ 257 $ 212 Interest cost 159 158 449 441 Expected return on plan assets (132 ) (204 ) (565 ) (442 ) Amortization and deferral 69 76 365 238 Net periodic benefit cost $ 96 $ 126 $ 506 $ 449 United States Plans International Plans Nine months ended Nine months ended December 31, 2017 January 1, 2017 December 31, 2017 January 1, 2017 Service cost $ — $ 278 $ 756 $ 658 Interest cost 493 498 1,325 1,402 Expected return on plan assets (372 ) (612 ) (1,670 ) (1,424 ) Amortization and deferral 228 340 1,076 756 Net periodic benefit cost $ 349 $ 504 $ 1,487 $ 1,392

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Stock-Based Compensation	Stock-Based Compensation As of December 31, 2017 , the Company maintains the 2017 Equity Incentive Plan (“2017 EIP”). The 2017 EIP reserved 3,177,477 shares of common stock for the grant of various classes of nonqualified stock options, restricted stock units, market condition-based share units and other forms of equity-based compensation. The Company recognized stock-based compensation expense associated with its equity incentive plans of $5,250 for the third quarter of fiscal 2018 and $4,699 for the third quarter of fiscal 2017 . Stock-based compensation expense was $14,773 for the nine months of fiscal 2018 and $14,556 for the nine months of fiscal 2017 . The Company recognizes compensation expense using the straight-line method over the vesting period of the awards. During the nine months of fiscal 2018 , the Company granted to non-employee directors 32,551 restricted stock units, pursuant to the 2017 EIP. During the nine months of fiscal 2018 , the Company granted to management and other key employees 169,703 non-qualified stock options and 60,008 market condition-based share units that vest three years from the date of grant, and 160,313 restricted stock units that vest 25% each year over four years from the date of grant. Common stock activity during the nine months of fiscal 2018 included the vesting of 149,458 restricted stock units and 142,426 market condition-based share units and the exercise of 58,595 stock options. As of December 31, 2017 , there were 549,192 non-qualified stock options, 635,712 restricted stock units and 349,078

Stockholders' Equity and Noncon

Stockholders' Equity and Noncontrolling Interests	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Stockholders' Equity and Noncontrolling Interests	Stockholders’ Equity and Noncontrolling Interests Common Stock The following demonstrates the change in the number of shares of common stock outstanding during the nine months ended December 31, 2017 : Shares outstanding as of March 31, 2017 43,447,536 Purchase of treasury stock (1,540,093 ) Shares issued towards equity-based compensation plans, net of equity awards surrendered for option price and taxes 219,374 Shares outstanding as of December 31, 2017 42,126,817 Accelerated Share Repurchase During the second quarter of fiscal 2018 , the Company entered into an accelerated share repurchase agreement (“ASR”) with a major financial institution to repurchase up to $100,000 of its common stock. The Company prepaid $100,000 and received an initial delivery of 1,278,976 shares with a fair market value of approximately $80,000 . The ASR is accounted for as a treasury stock repurchase, reducing the weighted average number of basic and diluted shares outstanding by the 1,278,976 shares initially received, and as a forward contract indexed to the Company's own common shares to reflect the future settlement provisions. Because the maximum repurchase will be $100,000 , as of December 31, 2017 , $20,000 representing the difference between the fair value of shares delivered and the maximum notional amount of $100,000 , is accounted for as an equity instrument and is included in additional paid-in capital. The ASR is not accounted for as a derivative instrument. No shares were received pursuant to the ASR during the current quarter. On January 9, 2018, the ASR was settled, and the Company received an additional 216,738 shares. See Note 15 - Subsequent Events, for more information. Treasury Stock During the nine months ended December 31, 2017 , the Company also acquired 261,117 shares for $21,191 through open market purchases. At December 31, 2017 and March 31, 2017 , the Company held 12,463,367 and 10,923,274 shares as treasury stock, respectively. Accumulated Other Comprehensive Income ( “ AOCI ” ) The components of AOCI, net of tax, as of December 31, 2017 and March 31, 2017 , are as follows: March 31, 2017 Before Reclassifications Amounts Reclassified from AOCI December 31, 2017 Pension funded status adjustment $ (25,555 ) $ — $ 996 $ (24,559 ) Net unrealized gain (loss) on derivative instruments 1,975 (309 ) 338 2,004 Foreign currency translation adjustment (129,244 ) 86,782 — (42,462 ) Accumulated other comprehensive (loss) income $ (152,824 ) $ 86,473 $ 1,334 $ (65,017 ) The following table presents reclassifications from AOCI during the third quarter ended December 31, 2017 : Components of AOCI Amounts Reclassified from AOCI Location of (Gain) Loss Recognized on Income Statement Derivatives in cash flow hedging relationships: Net gain on cash flow hedging derivative instruments $ (455 ) Cost of goods sold Tax expense 168 Net gain on derivative instruments, net of tax $ (287 ) Defined benefit pension costs: Prior service costs and deferrals $ 434 Net periodic benefit cost, included in cost of goods sold and operating expenses - See Note 10 Tax benefit (103 ) Net periodic benefit cost, net of tax $ 331 The following table presents reclassifications from AOCI during the third quarter ended January 1, 2017 : Components of AOCI Amounts Reclassified from AOCI Location of (Gain) Loss Recognized on Income Statement Derivatives in cash flow hedging relationships: Net gain on cash flow hedging derivative instruments $ (1,431 ) Cost of goods sold Tax expense 528 Net gain on derivative instruments, net of tax $ (903 ) Defined benefit pension costs: Prior service costs and deferrals $ 314 Net periodic benefit cost, included in cost of goods sold and operating expenses - See Note 10 Tax benefit (116 ) Net periodic benefit cost, net of tax $ 198 The following table presents reclassifications from AOCI during the nine months ended December 31, 2017 : Components of AOCI Amounts Reclassified from AOCI Location of (Gain) Loss Recognized on Income Statement Derivatives in cash flow hedging relationships: Net loss on cash flow hedging derivative instruments $ 537 Cost of goods sold Tax benefit (199 ) Net loss on derivative instruments, net of tax $ 338 Defined benefit pension costs: Prior service costs and deferrals $ 1,304 Net periodic benefit cost, included in cost of goods sold and operating expenses - See Note 10 Tax benefit (308 ) Net periodic benefit cost, net of tax $ 996 The following table presents reclassifications from AOCI during the nine months ended January 1, 2017 : Components of AOCI Amounts Reclassified from AOCI Location of (Gain) Loss Recognized on Income Statement Derivatives in cash flow hedging relationships: Net gain on cash flow hedging derivative instruments $ (2,481 ) Cost of goods sold Tax expense 915 Net gain on derivative instruments, net of tax $ (1,566 ) Defined benefit pension costs: Prior service costs and deferrals $ 1,096 Net periodic benefit cost, included in cost of goods sold and operating expenses - See Note 10 Tax benefit (349 ) Net periodic benefit cost, net of tax $ 747 The following demonstrates the change in equity attributable to EnerSys stockholders and nonredeemable noncontrolling interests during the nine months ended December 31, 2017 : Equity Attributable to EnerSys Stockholders Nonredeemable Noncontrolling Interests Total Equity Balance as of March 31, 2017 $ 1,103,456 $ 4,913 $ 1,108,369 Total comprehensive income: Net earnings 65,576 118 65,694 Net unrealized gain on derivative instruments, net of tax 29 — 29 Pension funded status adjustment, net of tax 996 — 996 Foreign currency translation adjustment 86,782 119 86,901 Total other comprehensive gain, net of tax 87,807 119 87,926 Total comprehensive income 153,383 237 153,620 Other changes in equity: Purchase of treasury stock including ASR (121,191 ) — (121,191 ) Cash dividends - common stock ($0.525 per share) (22,339 ) — (22,339 ) Other, including activity related to equity awards 7,515 — 7,515 Balance as of December 31, 2017 $ 1,120,824 $ 5,150 $ 1,125,974

Earnings Per Share

Earnings Per Share	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Earnings Per Share	Earnings Per Share The following table sets forth the reconciliation from basic to diluted weighted-average number of common shares outstanding and the calculations of net earnings per common share attributable to EnerSys stockholders. Quarter ended Nine months ended December 31, 2017 January 1, 2017 December 31, 2017 January 1, 2017 Net (loss) earnings attributable to EnerSys stockholders $ (25,847 ) $ 36,235 $ 65,576 $ 126,444 Weighted-average number of common shares outstanding: Basic 42,125,745 43,429,525 42,837,986 43,375,474 Dilutive effect of: Common shares from exercise and lapse of equity awards, net of shares assumed reacquired — 620,149 507,940 567,536 Diluted weighted-average number of common shares outstanding 42,125,745 44,049,674 43,345,926 43,943,010 Basic (loss) earnings per common share attributable to EnerSys stockholders $ (0.61 ) $ 0.83 $ 1.53 $ 2.92 Diluted (loss) earnings per common share attributable to EnerSys stockholders $ (0.61 ) $ 0.82 $ 1.51 $ 2.88 Anti-dilutive equity awards not included in diluted weighted-average common shares 279,066 62,470 264,517 232,542

Business Segments

Business Segments	9 Months Ended
	Dec. 31, 2017
Disclosure Schedule Of Financial Data For Company Reportable Business Segments And Product Lines [Abstract]
Business Segments	Business Segments The Company has three reportable business segments based on geographic regions, defined as follows: • Americas , which includes North and South America, with segment headquarters in Reading, Pennsylvania, USA; • EMEA , which includes Europe, the Middle East and Africa, with segment headquarters in Zug, Switzerland; and • Asia , which includes Asia, Australia and Oceania, with segment headquarters in Singapore. Summarized financial information related to the Company's reportable segments for the third quarter and nine months ended December 31, 2017 and January 1, 2017 is shown below: Quarter ended Nine months ended December 31, 2017 January 1, 2017 December 31, 2017 January 1, 2017 Net sales by segment to unaffiliated customers Americas $ 353,237 $ 313,972 $ 1,049,344 $ 968,516 EMEA 224,931 186,069 621,864 563,765 Asia 80,767 63,656 227,641 208,067 Total net sales $ 658,935 $ 563,697 $ 1,898,849 $ 1,740,348 Net sales by product line Reserve power $ 326,989 $ 271,291 $ 924,404 $ 844,781 Motive power 331,946 292,406 974,445 895,567 Total net sales $ 658,935 $ 563,697 $ 1,898,849 $ 1,740,348 Intersegment sales Americas $ 7,144 $ 6,319 $ 23,360 $ 19,304 EMEA 29,989 22,086 97,369 66,186 Asia 6,213 6,285 16,524 18,070 Total intersegment sales (1) $ 43,346 $ 34,690 $ 137,253 $ 103,560 Operating earnings by segment Americas $ 43,137 $ 45,949 $ 140,827 $ 139,149 EMEA 23,794 20,435 54,888 57,268 Asia 3,318 3,984 10,744 11,741 Restructuring charges - Americas (961 ) — (1,246 ) (892 ) Inventory adjustment relating to exit activities - EMEA — 502 — (2,157 ) Restructuring charges - EMEA (848 ) 1,153 (3,172 ) (3,663 ) Restructuring charges - Asia — — — (482 ) Legal proceedings charge - EMEA — (17,000 ) — (17,000 ) Total operating earnings (2) $ 68,440 $ 55,023 $ 202,041 $ 183,964 (1 ) Intersegment sales are presented on a cost-plus basis, which takes into consideration the effect of transfer prices between legal entities. (2 )

Subsequent Events

Subsequent Events	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Subsequent Events	Subsequent Events On January 9, 2018, the ASR was settled, and the Company received an additional 216,738 shares. The Company repurchased a total of 1,495,714 shares under the ASR for a total cash investment of $100,000 at an average price of $66.86 . On February 7, 2018, the Board of Directors approved a quarterly cash dividend of $0.175 per share of common stock to be paid on

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Dec. 31, 2017
Inventory Disclosure [Abstract]
Summary Of Inventories	Inventories, net consist of: December 31, 2017 March 31, 2017 Raw materials $ 96,666 $ 85,604 Work-in-process 138,540 107,177 Finished goods 186,764 167,913 Total $ 421,970 $ 360,694

Fair Value of Financial Instr23

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Financial Assets And (Liabilities), Measured At Fair Value On A Recurring Basis	The following tables represent the financial assets and (liabilities) measured at fair value on a recurring basis as of December 31, 2017 and March 31, 2017 , and the basis for that measurement: Total Fair Value Measurement December 31, 2017 Quoted Price in Significant Significant Lead forward contracts $ 47 $ — $ 47 $ — Foreign currency forward contracts (266 ) — (266 ) — Total derivatives $ (219 ) $ — $ (219 ) $ — Total Fair Value Measurement March 31, 2017 Quoted Price in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Lead forward contracts $ 1,163 $ — $ 1,163 $ — Foreign currency forward contracts (313 ) — (313 ) — Total derivatives $ 850 $ — $ 850 $ —
Carrying Amounts And Estimated Fair Values Of Company's Financial Instruments	The carrying amounts and estimated fair values of the Company’s derivatives and Notes at December 31, 2017 and March 31, 2017 were as follows: December 31, 2017 March 31, 2017 Carrying Fair Value Carrying Fair Value Financial assets: Derivatives (1) $ 47 $ 47 $ 1,163 $ 1,163 Financial liabilities: Notes (2) $ 300,000 $ 313,500 $ 300,000 $ 303,000 Derivatives (1) 266 266 313 313 (1) Represents lead and foreign currency forward contracts (see Note 4 for asset and liability positions of the lead and foreign currency forward contracts at December 31, 2017 and March 31, 2017 ). (2) The fair value amount of the Notes at December 31, 2017 and March 31, 2017 represent the trading value of the instruments.

Derivative Financial Instrume24

Derivative Financial Instruments (Tables)	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Fair Value of Derivative Instruments	Presented below in tabular form is information on the location and amounts of derivative fair values in the Consolidated Condensed Balance Sheets and derivative gains and losses in the Consolidated Condensed Statements of Income: Fair Value of Derivative Instruments December 31, 2017 and March 31, 2017 Derivatives and Hedging Activities Designated as Cash Flow Hedges Derivatives and Hedging Activities Not Designated as Hedging Instruments December 31, 2017 March 31, 2017 December 31, 2017 March 31, 2017 Prepaid and other current assets Lead forward contracts $ 47 $ 1,163 $ — $ — Foreign currency forward contracts — 11 14 — Total assets $ 47 $ 1,174 $ 14 $ — Accrued expenses Foreign currency forward contracts $ 280 $ — $ — $ 324 Total liabilities $ 280 $ — $ — $ 324
The Effect Of Derivative Instruments On Consolidated Condensed Statements Of Income	The Effect of Derivative Instruments on the Consolidated Condensed Statements of Income For the quarter ended December 31, 2017 Derivatives Designated as Cash Flow Hedges Pretax Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion) Location of Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Pretax Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Lead forward contracts $ (396 ) Cost of goods sold $ 2,266 Foreign currency forward contracts (87 ) Cost of goods sold (1,811 ) Total $ (483 ) $ 455 Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivatives Pretax Gain (Loss) Foreign currency forward contracts Other (income) expense, net $ 93 Total $ 93 The Effect of Derivative Instruments on the Consolidated Condensed Statements of Income For the quarter ended January 1, 2017 Derivatives Designated as Cash Flow Hedges Pretax Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion) Location of Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Pretax Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Lead forward contracts $ (2,362 ) Cost of goods sold $ 1,524 Foreign currency forward contracts 595 Cost of goods sold (93 ) Total $ (1,767 ) $ 1,431 Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivatives Pretax Gain (Loss) Foreign currency forward contracts Other (income) expense, net $ (25 ) Total $ (25 ) The Effect of Derivative Instruments on the Consolidated Condensed Statements of Income For the nine months ended December 31, 2017 Derivatives Designated as Cash Flow Hedges Pretax Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion) Location of Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Pretax Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Lead forward contracts $ 2,686 Cost of goods sold $ 2,177 Foreign currency forward contracts (3,175 ) Cost of goods sold (2,714 ) Total $ (489 ) $ (537 ) Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivatives Pretax Gain (Loss) Foreign currency forward contracts Other (income) expense, net $ 105 Total $ 105 The Effect of Derivative Instruments on the Consolidated Condensed Statements of Income For the nine months ended January 1, 2017 Derivatives Designated as Cash Flow Hedges Pretax Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion) Location of Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Pretax Gain (Loss) Reclassified from AOCI into Income (Effective Portion) Lead forward contracts $ 2,258 Cost of goods sold $ 2,800 Foreign currency forward contracts 873 Cost of goods sold (319 ) Total $ 3,131 $ 2,481 Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivatives Pretax Gain (Loss) Foreign currency forward contracts Other (income) expense, net $ (202 ) Total $ (202 )

Warranty (Tables)

Warranty (Tables)	9 Months Ended
	Dec. 31, 2017
Disclosure Analysis Of Changes In Liability For Product Warranties [Abstract]
Analysis Of Changes In Liability For Product Warranties	An analysis of changes in the liability for product warranties is as follows: Quarter ended Nine months ended December 31, 2017 January 1, 2017 December 31, 2017 January 1, 2017 Balance at beginning of period $ 47,113 $ 48,112 $ 46,116 $ 48,422 Current period provisions 6,204 4,085 13,012 14,932 Costs incurred (3,843 ) (4,250 ) (10,880 ) (12,492 ) Foreign currency translation adjustment 23 (1,720 ) 1,249 (4,635 ) Balance at end of period $ 49,497 $ 46,227 $ 49,497 $ 46,227

Restructuring (Tables)

Restructuring (Tables)	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Reconciliation of Restructuring Reserve	A roll-forward of the restructuring reserve is as follows: Employee Severance Other Total Balance as of March 31, 2017 $ 2,668 $ 144 $ 2,812 Accrued 3,890 317 4,207 Costs incurred (3,421 ) (462 ) (3,883 ) Foreign currency impact 249 1 250 Balance as of December 31, 2017 $ 3,386 $ — $ 3,386

Debt (Tables)

Debt (Tables)	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Long-Term Debt And Capital Lease Obligations	The following summarizes the Company’s long-term debt as of December 31, 2017 and March 31, 2017 : December 31, 2017 March 31, 2017 Principal Unamortized Issuance Costs Principal Unamortized Issuance Costs 5.00% Senior Notes due 2023 $ 300,000 $ 3,278 $ 300,000 $ 3,746 2017 Credit Facility, due 2022 395,300 3,001 — — 2011 Credit Facility, due 2018 — — 292,500 1,145 $ 695,300 $ 6,279 $ 592,500 $ 4,891 Less: Unamortized issuance costs 6,279 4,891 Long-term debt, net of unamortized issuance costs $ 689,021 $ 587,609

Retirement Plans (Tables)

Retirement Plans (Tables)	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Net Periodic Benefit Cost Related To Defined Benefit Pension Plans	The following tables present the components of the Company’s net periodic benefit cost related to its defined benefit pension plans: United States Plans International Plans Quarter ended Quarter ended December 31, 2017 January 1, 2017 December 31, 2017 January 1, 2017 Service cost $ — $ 96 $ 257 $ 212 Interest cost 159 158 449 441 Expected return on plan assets (132 ) (204 ) (565 ) (442 ) Amortization and deferral 69 76 365 238 Net periodic benefit cost $ 96 $ 126 $ 506 $ 449 United States Plans International Plans Nine months ended Nine months ended December 31, 2017 January 1, 2017 December 31, 2017 January 1, 2017 Service cost $ — $ 278 $ 756 $ 658 Interest cost 493 498 1,325 1,402 Expected return on plan assets (372 ) (612 ) (1,670 ) (1,424 ) Amortization and deferral 228 340 1,076 756 Net periodic benefit cost $ 349 $ 504 $ 1,487 $ 1,392

Stockholders' Equity and Nonc29

Stockholders' Equity and Noncontrolling Interests (Tables)	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Change In Number Of Shares Of Common Stock Outstanding	The following demonstrates the change in the number of shares of common stock outstanding during the nine months ended December 31, 2017 : Shares outstanding as of March 31, 2017 43,447,536 Purchase of treasury stock (1,540,093 ) Shares issued towards equity-based compensation plans, net of equity awards surrendered for option price and taxes 219,374 Shares outstanding as of December 31, 2017 42,126,817
Components Of Accumulated Other Comprehensive Income	The components of AOCI, net of tax, as of December 31, 2017 and March 31, 2017 , are as follows: March 31, 2017 Before Reclassifications Amounts Reclassified from AOCI December 31, 2017 Pension funded status adjustment $ (25,555 ) $ — $ 996 $ (24,559 ) Net unrealized gain (loss) on derivative instruments 1,975 (309 ) 338 2,004 Foreign currency translation adjustment (129,244 ) 86,782 — (42,462 ) Accumulated other comprehensive (loss) income $ (152,824 ) $ 86,473 $ 1,334 $ (65,017 )
Reclassification from Accumulated Other Comprehensive Income	The following table presents reclassifications from AOCI during the third quarter ended December 31, 2017 : Components of AOCI Amounts Reclassified from AOCI Location of (Gain) Loss Recognized on Income Statement Derivatives in cash flow hedging relationships: Net gain on cash flow hedging derivative instruments $ (455 ) Cost of goods sold Tax expense 168 Net gain on derivative instruments, net of tax $ (287 ) Defined benefit pension costs: Prior service costs and deferrals $ 434 Net periodic benefit cost, included in cost of goods sold and operating expenses - See Note 10 Tax benefit (103 ) Net periodic benefit cost, net of tax $ 331 The following table presents reclassifications from AOCI during the third quarter ended January 1, 2017 : Components of AOCI Amounts Reclassified from AOCI Location of (Gain) Loss Recognized on Income Statement Derivatives in cash flow hedging relationships: Net gain on cash flow hedging derivative instruments $ (1,431 ) Cost of goods sold Tax expense 528 Net gain on derivative instruments, net of tax $ (903 ) Defined benefit pension costs: Prior service costs and deferrals $ 314 Net periodic benefit cost, included in cost of goods sold and operating expenses - See Note 10 Tax benefit (116 ) Net periodic benefit cost, net of tax $ 198 The following table presents reclassifications from AOCI during the nine months ended December 31, 2017 : Components of AOCI Amounts Reclassified from AOCI Location of (Gain) Loss Recognized on Income Statement Derivatives in cash flow hedging relationships: Net loss on cash flow hedging derivative instruments $ 537 Cost of goods sold Tax benefit (199 ) Net loss on derivative instruments, net of tax $ 338 Defined benefit pension costs: Prior service costs and deferrals $ 1,304 Net periodic benefit cost, included in cost of goods sold and operating expenses - See Note 10 Tax benefit (308 ) Net periodic benefit cost, net of tax $ 996 The following table presents reclassifications from AOCI during the nine months ended January 1, 2017 : Components of AOCI Amounts Reclassified from AOCI Location of (Gain) Loss Recognized on Income Statement Derivatives in cash flow hedging relationships: Net gain on cash flow hedging derivative instruments $ (2,481 ) Cost of goods sold Tax expense 915 Net gain on derivative instruments, net of tax $ (1,566 ) Defined benefit pension costs: Prior service costs and deferrals $ 1,096 Net periodic benefit cost, included in cost of goods sold and operating expenses - See Note 10 Tax benefit (349 ) Net periodic benefit cost, net of tax $ 747
Equity Attributable To Parent And Noncontrolling Interests [Table Text Block]	The following demonstrates the change in equity attributable to EnerSys stockholders and nonredeemable noncontrolling interests during the nine months ended December 31, 2017 : Equity Attributable to EnerSys Stockholders Nonredeemable Noncontrolling Interests Total Equity Balance as of March 31, 2017 $ 1,103,456 $ 4,913 $ 1,108,369 Total comprehensive income: Net earnings 65,576 118 65,694 Net unrealized gain on derivative instruments, net of tax 29 — 29 Pension funded status adjustment, net of tax 996 — 996 Foreign currency translation adjustment 86,782 119 86,901 Total other comprehensive gain, net of tax 87,807 119 87,926 Total comprehensive income 153,383 237 153,620 Other changes in equity: Purchase of treasury stock including ASR (121,191 ) — (121,191 ) Cash dividends - common stock ($0.525 per share) (22,339 ) — (22,339 ) Other, including activity related to equity awards 7,515 — 7,515 Balance as of December 31, 2017 $ 1,120,824 $ 5,150 $ 1,125,974

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Schedule of Weighted Average Number of Shares	The following table sets forth the reconciliation from basic to diluted weighted-average number of common shares outstanding and the calculations of net earnings per common share attributable to EnerSys stockholders. Quarter ended Nine months ended December 31, 2017 January 1, 2017 December 31, 2017 January 1, 2017 Net (loss) earnings attributable to EnerSys stockholders $ (25,847 ) $ 36,235 $ 65,576 $ 126,444 Weighted-average number of common shares outstanding: Basic 42,125,745 43,429,525 42,837,986 43,375,474 Dilutive effect of: Common shares from exercise and lapse of equity awards, net of shares assumed reacquired — 620,149 507,940 567,536 Diluted weighted-average number of common shares outstanding 42,125,745 44,049,674 43,345,926 43,943,010 Basic (loss) earnings per common share attributable to EnerSys stockholders $ (0.61 ) $ 0.83 $ 1.53 $ 2.92 Diluted (loss) earnings per common share attributable to EnerSys stockholders $ (0.61 ) $ 0.82 $ 1.51 $ 2.88 Anti-dilutive equity awards not included in diluted weighted-average common shares 279,066 62,470 264,517 232,542

Business Segments Business Segm

Business Segments Business Segments (Tables)	9 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Selected Financial Data for Reportable Business Segments and Product Lines	Summarized financial information related to the Company's reportable segments for the third quarter and nine months ended December 31, 2017 and January 1, 2017 is shown below: Quarter ended Nine months ended December 31, 2017 January 1, 2017 December 31, 2017 January 1, 2017 Net sales by segment to unaffiliated customers Americas $ 353,237 $ 313,972 $ 1,049,344 $ 968,516 EMEA 224,931 186,069 621,864 563,765 Asia 80,767 63,656 227,641 208,067 Total net sales $ 658,935 $ 563,697 $ 1,898,849 $ 1,740,348 Net sales by product line Reserve power $ 326,989 $ 271,291 $ 924,404 $ 844,781 Motive power 331,946 292,406 974,445 895,567 Total net sales $ 658,935 $ 563,697 $ 1,898,849 $ 1,740,348 Intersegment sales Americas $ 7,144 $ 6,319 $ 23,360 $ 19,304 EMEA 29,989 22,086 97,369 66,186 Asia 6,213 6,285 16,524 18,070 Total intersegment sales (1) $ 43,346 $ 34,690 $ 137,253 $ 103,560 Operating earnings by segment Americas $ 43,137 $ 45,949 $ 140,827 $ 139,149 EMEA 23,794 20,435 54,888 57,268 Asia 3,318 3,984 10,744 11,741 Restructuring charges - Americas (961 ) — (1,246 ) (892 ) Inventory adjustment relating to exit activities - EMEA — 502 — (2,157 ) Restructuring charges - EMEA (848 ) 1,153 (3,172 ) (3,663 ) Restructuring charges - Asia — — — (482 ) Legal proceedings charge - EMEA — (17,000 ) — (17,000 ) Total operating earnings (2) $ 68,440 $ 55,023 $ 202,041 $ 183,964 (1 ) Intersegment sales are presented on a cost-plus basis, which takes into consideration the effect of transfer prices between legal entities. (2 ) The Company does not allocate interest expense or other (income) expense to the reportable segments.

Basis of Presentation Basis of

Basis of Presentation Basis of Presentation (Details)	3 Months Ended
	Jul. 03, 2016USD ($)
Basis of Presentation [Abstract]
Excess tax benefits	$ 137

Inventories - (Details)

Inventories - (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 31, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 96,666	$ 85,604
Work-in-process	138,540	107,177
Finished goods	186,764	167,913
Total	$ 421,970	$ 360,694

Fair Value of Financial Instr34

Fair Value of Financial Instruments - Financial Assets and (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative fair value	$ (219)	$ 850
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative fair value	(219)	850
Lead forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative fair value	47	1,163
Lead forward contracts | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative fair value	47	1,163
Foreign currency forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative fair value	(266)	(313)
Foreign currency forward contracts | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative fair value	$ (266)	$ (313)

Fair Value of Financial Instr35

Fair Value of Financial Instruments - (Additional Information) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 31, 2017	Apr. 23, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Face value of trades, percentage	104.00%	101.00%
5.00% Senior Notes due 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate	5.00%		5.00%
Long-term debt	$ 300,000	$ 300,000	$ 300,000

Fair Value of Financial Instr36

Fair Value of Financial Instruments - Carrying Amounts and Estimated Fair Values (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 31, 2017
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative asset	$ 47	$ 1,163
Notes	300,000	300,000
Derivative liability	266	313
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative asset	47	1,163
Notes	313,500	303,000
Derivative liability	$ 266	$ 313

Derivative Financial Instrume37

Derivative Financial Instruments - Location and Amounts of Derivative Fair Values (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 31, 2017
Derivatives and Hedging Activities Designated as Cash Flow Hedges
Derivatives, Fair Value [Line Items]
Derivatives assets, fair value	$ 47	$ 1,174
Derivatives and Hedging Activities Designated as Cash Flow Hedges | Accrued expenses
Derivatives, Fair Value [Line Items]
Derivatives liabilities, fair value	280	0
Derivatives and Hedging Activities Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Derivatives assets, fair value	14	0
Derivatives and Hedging Activities Not Designated as Hedging Instruments | Accrued expenses
Derivatives, Fair Value [Line Items]
Derivatives liabilities, fair value	0	324
Lead forward contracts | Derivatives and Hedging Activities Designated as Cash Flow Hedges | Prepaid and other current assets
Derivatives, Fair Value [Line Items]
Derivatives assets, fair value	47	1,163
Lead forward contracts | Derivatives and Hedging Activities Not Designated as Hedging Instruments | Prepaid and other current assets
Derivatives, Fair Value [Line Items]
Derivatives assets, fair value	0	0
Foreign currency forward contracts | Derivatives and Hedging Activities Designated as Cash Flow Hedges | Prepaid and other current assets
Derivatives, Fair Value [Line Items]
Derivatives assets, fair value	0	11
Foreign currency forward contracts | Derivatives and Hedging Activities Designated as Cash Flow Hedges | Accrued expenses
Derivatives, Fair Value [Line Items]
Derivatives liabilities, fair value	280	0
Foreign currency forward contracts | Derivatives and Hedging Activities Not Designated as Hedging Instruments | Prepaid and other current assets
Derivatives, Fair Value [Line Items]
Derivatives assets, fair value	14	0
Foreign currency forward contracts | Derivatives and Hedging Activities Not Designated as Hedging Instruments | Accrued expenses
Derivatives, Fair Value [Line Items]
Derivatives liabilities, fair value	$ 0	$ 324

Derivative Financial Instrume38

Derivative Financial Instruments - Derivatives Designated as Cash Flow Hedges (Details) - Derivatives Designated as Cash Flow Hedges - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Dec. 31, 2017	Jan. 01, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Pretax Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	$ (483)	$ (1,767)	$ (489)	$ 3,131
Pretax Gain (Loss) Reclassified from AOCI into Income (Effective Portion)	455	1,431	(537)	2,481
Lead forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Pretax Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	(396)	(2,362)	2,686	2,258
Lead forward contracts | Cost of Sales
Derivative Instruments, Gain (Loss) [Line Items]
Pretax Gain (Loss) Reclassified from AOCI into Income (Effective Portion)	2,266	1,524	2,177	2,800
Foreign currency forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Pretax Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	(87)	595	(3,175)	873
Foreign currency forward contracts | Cost of Sales
Derivative Instruments, Gain (Loss) [Line Items]
Pretax Gain (Loss) Reclassified from AOCI into Income (Effective Portion)	$ (1,811)	$ (93)	$ (2,714)	$ (319)

Derivative Financial Instrume39

Derivative Financial Instruments - Derivatives Not Designated as Hedging Instruments (Details) - Derivatives Not Designated as Hedging Instruments - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Dec. 31, 2017	Jan. 01, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives Not Designated as Hedging Instruments	$ 93	$ (25)	$ 105	$ (202)
Foreign currency forward contracts | Other Income Expense
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives Not Designated as Hedging Instruments	$ 93	$ (25)	$ 105	$ (202)

- Derivative Financial Instrume

- Derivative Financial Instruments (Additional Information) (Details) $ in Thousands, lb in Millions	9 Months Ended
	Dec. 31, 2017USD ($)lb	Mar. 31, 2017USD ($)lb
Cost of Sales
Derivatives, Fair Value [Line Items]
Foreign currency cash flow hedge loss to be reclassified during next 12 months	$ (3,133)
Lead forward contracts
Derivatives, Fair Value [Line Items]
Notional amount in pounds | lb	54	45
Fair value of hedges, net	$ 60,849	$ 46,550
Foreign currency forward contracts
Derivatives, Fair Value [Line Items]
Notional amount	52,801	30,751
Foreign currency forward contracts | Derivatives and Hedging Activities Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Notional amount	$ 24,132	$ 13,560
Maximum | Lead forward contracts
Derivatives, Fair Value [Line Items]
Derivative, remaining maturity	1 year

- (Additional Information) (Det

- (Additional Information) (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Dec. 31, 2017	Jan. 01, 2017	Mar. 31, 2018
Income Tax Contingency [Line Items]
Provisional income tax expense comprised of foreign tax effects and deferred tax assets and liabilities	$ 77,347
Transition tax	94,000
Current portion of transition tax liability	7,520
Noncurrent portion of transition tax liability	86,480
Tax benefit from remeasurement of deferred tax balance	14,706
Provisional tax benefit related to reduction of federal tax rate	$ 1,947
Effective income tax rates	141.20%	26.70%	63.20%	25.70%
Foreign income as a percentage or worldwide income			$ 0.64	$ 0.60
Foreign effective income tax rates			11.40%	15.90%
Tax rate of Swiss subsidiary			6.00%
Scenario, Forecast
Income Tax Contingency [Line Items]
Blended federal statutory tax rate					31.50%

Warranty - Analysis of Changes

Warranty - Analysis of Changes in the Liability (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Dec. 31, 2017	Jan. 01, 2017
Disclosure Analysis Of Changes In Liability For Product Warranties [Abstract]
Balance at beginning of period	$ 47,113	$ 48,112	$ 46,116	$ 48,422
Current period provisions	6,204	4,085	13,012	14,932
Costs incurred	(3,843)	(4,250)	(10,880)	(12,492)
Foreign currency translation adjustment	23	(1,720)	1,249	(4,635)
Balance at end of period	$ 49,497	$ 46,227	$ 49,497	$ 46,227

Commitments, Contingencies an43

Commitments, Contingencies and Litigation - (Additional Information) (Details) - USD ($) $ in Thousands	1 Months Ended			9 Months Ended	12 Months Ended
	Jul. 31, 2017	Jun. 30, 2017	Feb. 29, 2016	Dec. 31, 2017	Mar. 31, 2017
Commitments, Contingencies And Litigation [Line Items]
Reserves for anti-competition investigations				$ 2,058	$ 25,551
Provision for environmental liabilities				1,117	1,123
Belgium Anti-Competition Proceeding
Commitments, Contingencies And Litigation [Line Items]
Penalties paid relating to anti-competition investigations			$ 1,962
Reserves for anti-competition investigations				2,058	1,830
Germany Anti-Competition Proceeding
Commitments, Contingencies And Litigation [Line Items]
Penalties paid relating to anti-competition investigations		$ 14,811
Reserves for anti-competition investigations				0	13,463
Estimate of possible loss				11,415
Dutch Anti-Competition Proceeding
Commitments, Contingencies And Litigation [Line Items]
Penalties paid relating to anti-competition investigations	$ 11,229
Reserves for anti-competition investigations				$ 0	$ 10,258

Restructuring - Roll-forward of

Restructuring - Roll-forward of Restructuring Reserve (Details) $ in Thousands	9 Months Ended
	Dec. 31, 2017USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, beginning balance	$ 2,812
Accrued	4,207
Costs incurred	(3,883)
Foreign currency impact	250
Restructuring reserve, ending balance	3,386
Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, beginning balance	2,668
Accrued	3,890
Costs incurred	(3,421)
Foreign currency impact	249
Restructuring reserve, ending balance	3,386
Other
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, beginning balance	144
Accrued	317
Costs incurred	(462)
Foreign currency impact	1
Restructuring reserve, ending balance	$ 0

Restructuring - (Additional Inf

Restructuring - (Additional Information) (Details) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Dec. 31, 2017USD ($)Employee	Jul. 02, 2017USD ($)	Jan. 01, 2017USD ($)	Dec. 31, 2017USD ($)Employee	Jan. 01, 2017USD ($)	Mar. 31, 2017USD ($)Employee	Mar. 31, 2016USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring and other exit (credits)	$ 1,808		$ (1,153)	$ 4,417	$ 5,037
Restructuring costs incurred				3,883
Write-off of assets relating to restructuring charges				210	$ 1,435
Restructuring reserve	3,386			3,386		$ 2,812
Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred				3,421
Restructuring reserve	3,386			3,386		2,668
Facility Closing
Restructuring Cost and Reserve [Line Items]
Restructuring and other exit (credits)	75
Loss on sale of building	210
European Operations | Restructurings Related To Improving Efficiency Of Manufacturing Operations In EMEA
Restructuring Cost and Reserve [Line Items]
Restructuring and other exit (credits)	6,568			85		1,251	$ 5,232
Restructuring costs incurred				499		3,037	$ 2,993
Other restructuring charges	407
European Operations | Restructurings Related To Improving Efficiency Of Manufacturing Operations In EMEA | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	$ 6,161
Number of positions eliminated | Employee	130
European Operations | Restructurings Related To Improving Efficiency Related to Motive Power Assembly and Distribution Center
Restructuring Cost and Reserve [Line Items]
Restructuring and other exit (credits)				1,610		3,104
Restructuring costs incurred				1,725		749
Write-off of assets relating to restructuring charges						$ 4,700
Expected reduction in number of employees | Employee						45
Restructuring reserve	$ 2,406			2,406
European Operations | Restructurings Related To Improving Efficiency Related To Supply Chain And General Operations
Restructuring Cost and Reserve [Line Items]
Restructuring and other exit (credits)				1,477
Restructuring costs incurred				1,069
Write-off of assets relating to restructuring charges				$ 3,400
Expected reduction in number of employees | Employee				50
Restructuring reserve	406			$ 406
Expected additional restructuring charges	1,900			1,900
Asia | Restructurings Related To Manufacturing Facility in Jiangdu
Restructuring Cost and Reserve [Line Items]
Restructuring and other exit (credits)				0		$ 779
Restructuring costs incurred				129		$ 648
Asia | Restructurings Related To Manufacturing Facility in Jiangdu | Cash Charges
Restructuring Cost and Reserve [Line Items]
Write-off of assets relating to restructuring charges		$ 779
Americas | Restructurings Related To Improving Efficiencies of General Operations in the Americas
Restructuring Cost and Reserve [Line Items]
Restructuring and other exit (credits)				960
Restructuring costs incurred				386
Write-off of assets relating to restructuring charges				$ 1,000
Expected reduction in number of employees | Employee				60
Restructuring reserve	$ 574			$ 574

Debt - Long-term Debt Including

Debt - Long-term Debt Including Capital Lease Obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 31, 2017	Apr. 23, 2015
Debt Instrument [Line Items]
Debt and capital lease obligations	$ 695,300	$ 592,500
Unamortized Issuance Costs	6,279	4,891
Long-term debt, net of unamortized issuance costs	689,021	587,609
5.00% Senior Notes due 2023
Debt Instrument [Line Items]
Long-term debt	300,000	300,000	$ 300,000
Unamortized Issuance Costs	3,278	3,746
Secured Debt | Incremental Commitment Agreement | 2017 Credit Facility, due 2022
Debt Instrument [Line Items]
Incremental term loan commitment	395,300	0
Unamortized Issuance Costs	3,001	0
Secured Debt | Incremental Commitment Agreement | 2011 Credit Facility, due 2018
Debt Instrument [Line Items]
Incremental term loan commitment	0	292,500
Unamortized Issuance Costs	$ 0	$ 1,145

Debt - (Additional Information)

Debt - (Additional Information) (Details) - USD ($)	Aug. 04, 2017	Dec. 31, 2017	Jan. 01, 2017	Dec. 31, 2017	Jan. 01, 2017	Aug. 03, 2017	Mar. 31, 2017	Apr. 23, 2015
Debt Instrument [Line Items]
Increase in borrowing capacity limit	$ 325,000,000
Company owned capital stock, percentage securing senior secured credit facility	65.00%
Short-term debt		$ 16,842,000		$ 16,842,000			$ 18,359,000
Short-term debt, weighted average interest rate		8.00%		8.00%			7.00%
Debt issuance costs	$ 2,677,000			$ 2,677,000	$ 0
Write off of debt issuance costs	301,000
Amortization expense relating to debt issuance costs and included in interest expense		$ 314,000	$ 347,000	988,000	$ 1,041,000
Deferred issuance costs, net of accumulated amortization		6,279,000		6,279,000			$ 4,891,000
5.00% Senior Notes due 2023
Debt Instrument [Line Items]
Long-term debt		$ 300,000,000		$ 300,000,000			300,000,000	$ 300,000,000
Interest rate		5.00%		5.00%				5.00%
Convertible Notes Payable
Debt Instrument [Line Items]
Available lines of credit		$ 503,807,000		$ 503,807,000			475,947,000
Stand by letters of credit		3,074,000		3,074,000			2,189,000
Outstanding amount		150,832,000		150,832,000			$ 142,872,000
2017 Credit Facility, due 2022 | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	600,000,000
Available lines of credit		245,300,000		245,300,000
2017 Credit Facility, due 2022 | Secured Debt
Debt Instrument [Line Items]
Debt instrument, face amount	150,000,000
Available lines of credit		$ 150,000,000		$ 150,000,000
2011 Credit Facility, due 2018 | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity						$ 500,000,000
Available lines of credit	240,000,000
2011 Credit Facility, due 2018 | Secured Debt
Debt Instrument [Line Items]
Debt instrument, face amount						$ 150,000,000
Available lines of credit	$ 123,750,000
LIBOR | 2017 Revolver And 2017 Term Loan
Debt Instrument [Line Items]
Basis spread on variable rate	1.25%
LIBOR | 2017 Revolver And 2017 Term Loan | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	1.25%
LIBOR | 2017 Revolver And 2017 Term Loan | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%
Federal Funds Effective Rate | 2017 Revolver And 2017 Term Loan
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
Eurocurrency Base Rate | 2017 Revolver And 2017 Term Loan
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
Debt Instrument Quarterly Installments Beginning December 31, 2018 Through December 30, 2019
Debt Instrument [Line Items]
Debt instrument, periodic payment	$ 1,875,000
Debt Instrument Quarterly Installments Beginning December 31, 2019 Through December 30, 2020
Debt Instrument [Line Items]
Debt instrument, periodic payment	2,813,000
Debt Instrument Quarterly Installments Beginning December 31, 2020 Through September 29, 2022
Debt Instrument [Line Items]
Debt instrument, periodic payment	3,750,000
Debt Instrument Final Installments Payable On September 30, 2022
Debt Instrument [Line Items]
Debt instrument, periodic payment	$ 105,000,000

Retirement Plans -Net Periodic

Retirement Plans -Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Dec. 31, 2017	Jan. 01, 2017
United States Pension Plans of US Entity, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 96	$ 0	$ 278
Interest cost	159	158	493	498
Expected return on plan assets	(132)	(204)	(372)	(612)
Amortization and deferral	69	76	228	340
Net periodic benefit cost	96	126	349	504
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	257	212	756	658
Interest cost	449	441	1,325	1,402
Expected return on plan assets	(565)	(442)	(1,670)	(1,424)
Amortization and deferral	365	238	1,076	756
Net periodic benefit cost	$ 506	$ 449	$ 1,487	$ 1,392

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Dec. 31, 2017	Jan. 01, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grants	3,177,477		3,177,477
Equity-based compensation expense	$ 5,250	$ 4,699	$ 14,773	$ 14,556
Stock options exercised (in shares)			58,595,000
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested restricted stock and restricted stock units (in shares)			149,458,000
Stock option grants outstanding (in shares)	635,712,000		635,712,000
Nonqualified Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option grants outstanding (in shares)	549,192,000		549,192,000
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested restricted stock and restricted stock units (in shares)			142,426,000
Stock option grants outstanding (in shares)	349,078,000		349,078,000
Non-employee Directors | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock unit grants during period (in shares)			32,551,000
Management | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock unit grants during period (in shares)			160,313,000
Percentage of restricted stock units granted, vested per year			25.00%
Vesting period			4 years
Management | Nonqualified Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted (in shares)			169,703,000
Vesting period			3 years
Management | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock unit grants during period (in shares)			60,008,000
Vesting period			3 years

Stockholders' Equity and Nonc50

Stockholders' Equity and Noncontrolling Interests - Change in the Number of Shares of Common Stock Outstanding (Details)	9 Months Ended
	Dec. 31, 2017shares
Equity [Abstract]
Shares outstanding, beginning balance (in shares)	43,447,536
Purchase of treasury stock (in shares)	(1,540,093)
Shares issued towards equity-based compensation plans, net of equity awards surrendered for option price and taxes (in shares)	219,374
Shares outstanding, ending balance (in shares)	42,126,817

Stockholders' Equity and Nonc51

Stockholders' Equity and Noncontrolling Interests - Components of Accumulated Other Comprehensive Income (Details) $ in Thousands	9 Months Ended
	Dec. 31, 2017USD ($)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning balance	$ 1,108,369
Ending balance	1,125,974
Pension funded status adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning balance	25,555
Before Reclassifications	0
Amounts Reclassified from AOCI	(996)
Ending balance	24,559
Net unrealized gain (loss) on derivative instruments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning balance	1,975
Before Reclassifications	309
Amounts Reclassified from AOCI	338
Ending balance	2,004
Foreign currency translation adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning balance	(129,244)
Before Reclassifications	(86,782)
Amounts Reclassified from AOCI	0
Ending balance	(42,462)
Accumulated other comprehensive (loss) income
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning balance	(152,824)
Before Reclassifications	86,473
Amounts Reclassified from AOCI	1,334
Ending balance	$ (65,017)

Stockholders' Equity and Nonc52

Stockholders' Equity and Noncontrolling Interests - Reclassifications from AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Dec. 31, 2017	Jan. 01, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net gain on cash flow hedging derivative instruments	$ (491,970)	$ (408,315)	$ (1,408,913)	$ (1,254,678)
Derivatives in cash flow hedging relationships
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax expense (benefit)	168	528	(199)	915
Net of tax	(287)	(903)	338	(1,566)
Derivatives in cash flow hedging relationships | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net gain on cash flow hedging derivative instruments	(455)	(1,431)	(537)	(2,481)
Defined benefit pension costs
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior service costs and deferrals	434	314	1,304	1,096
Tax expense (benefit)	(103)	(116)	(308)	(349)
Net of tax	$ 331	$ 198	$ 996	$ 747

Stockholders' Equity and Nonc53

Stockholders' Equity and Noncontrolling Interests - Noncontrolling Interests (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Dec. 31, 2017	Jan. 01, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			$ 4,913
Net earnings	$ (68)	$ (860)	(118)	$ 1,937
Pension funded status adjustment, net of tax	331	198	996	747
Total other comprehensive gain (loss), net of tax	13,797	(54,573)	87,926	(73,764)
Total comprehensive income	(11,982)	$ (17,478)	153,620	50,743
Dividends paid to stockholders			(22,339)	(22,800)
Other, including activity related to equity awards			758	$ 5
Ending balance	$ 5,150		$ 5,150
Dividends declared (in dollars per share)	$ 0.175	$ 0.175	$ 0.525	$ 0.525
Equity Attributable to EnerSys Stockholders
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			$ 1,103,456
Net earnings			(65,576)
Net unrealized gain on derivative instruments, net of tax			29
Pension funded status adjustment, net of tax			996
Foreign currency translation adjustment			86,782
Total other comprehensive gain (loss), net of tax			87,807
Total comprehensive income			153,383
Purchase of treasury stock including ASR			(121,191)
Dividends paid to stockholders			(22,339)
Other, including activity related to equity awards			7,515
Ending balance	$ 1,120,824		1,120,824
Nonredeemable Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			4,913
Net unrealized gain on derivative instruments, net of tax			0
Pension funded status adjustment, net of tax			0
Foreign currency translation adjustment			119
Total other comprehensive gain (loss), net of tax			119
Total comprehensive income			237
Purchase of treasury stock including ASR			0
Dividends paid to stockholders			0
Other, including activity related to equity awards			0
Ending balance	5,150		5,150
Total Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			1,108,369
Net earnings			65,694
Net unrealized gain on derivative instruments, net of tax			29
Pension funded status adjustment, net of tax			996
Foreign currency translation adjustment			86,901
Total other comprehensive gain (loss), net of tax			87,926
Total comprehensive income			153,620
Purchase of treasury stock including ASR			(121,191)
Dividends paid to stockholders			(22,339)
Other, including activity related to equity awards			7,515
Ending balance	$ 1,125,974		$ 1,125,974

Stockholders' Equity and Nonc54

Stockholders' Equity and Noncontrolling Interests - Additional Information (Details) - USD ($)	Jan. 09, 2018	Jan. 09, 2018	Dec. 31, 2017	Dec. 31, 2017	Mar. 31, 2017
Class of Stock [Line Items]
Treasury stock purchased (in shares)				1,540,093
Treasury stock (in shares)			12,463,367	12,463,367	10,923,274
ASR Agreement
Class of Stock [Line Items]
Stock repurchase program, authorized amount			$ 100,000	$ 100,000
Stock repurchase program, amount prepaid			$ 100,000
Treasury stock purchased (in shares)			1,278,976
Fair market value of treasury stock purchased			$ 80,000
Difference between fair value of shares delivered and maximum notional amount				$ 20,000
Open Market Purchases
Class of Stock [Line Items]
Treasury stock purchased (in shares)				261,117
Treasury stock purchased, value				$ 21,191,000
Subsequent Event | ASR Agreement
Class of Stock [Line Items]
Shares repurchased during period (in shares)	216,738	1,495,714

Earnings Per Share - Reconcilia

Earnings Per Share - Reconciliation from Basic to Diluted Average Common Shares (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Dec. 31, 2017	Jan. 01, 2017
Earnings Per Share [Abstract]
Net (loss) earnings attributable to EnerSys stockholders	$ (25,847)	$ 36,235	$ 65,576	$ 126,444
Basic weighted-average number of common shares outstanding (in shares)	42,125,745	43,429,525	42,837,986	43,375,474
Common shares from exercise and lapse of equity awards, net of shares assumed reacquired (in shares)	0	620,149	507,940	567,536
Diluted weighted-average number of common shares outstanding (in shares)	42,125,745	44,049,674	43,345,926	43,943,010
Basic earnings (loss) per common share attributable to EnerSys stockholders (in dollars per share)	$ (0.61)	$ 0.83	$ 1.53	$ 2.92
Diluted earnings (loss) per common share attributable to EnerSys stockholders (in dollars per share)	$ (0.61)	$ 0.82	$ 1.51	$ 2.88
Anti-dilutive equity awards not included in diluted weighted-average common shares (in shares)	279,066	62,470	264,517	232,542

Business Segments - (Details)

Business Segments - (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017USD ($)	Jan. 01, 2017USD ($)	Dec. 31, 2017USD ($)segment	Jan. 01, 2017USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			3
Net sales by segment to unaffiliated customers	$ 658,935	$ 563,697	$ 1,898,849	$ 1,740,348
Net sales by product line	658,935	563,697	1,898,849	1,740,348
Intersegment sales	43,346	34,690	137,253	103,560
Operating earnings by segment	68,440	55,023	202,041	183,964
Restructuring charges	(1,808)	1,153	(4,417)	(5,037)
Intersegment sales	0	(17,000)	0	(17,000)
Inventory adjustment relating to exit activities - EMEA	0	502	0	(2,157)
Reserve power
Segment Reporting Information [Line Items]
Net sales by product line	326,989	271,291	924,404	844,781
Motive power
Segment Reporting Information [Line Items]
Net sales by product line	331,946	292,406	974,445	895,567
Americas
Segment Reporting Information [Line Items]
Net sales by segment to unaffiliated customers	353,237	313,972	1,049,344	968,516
Intersegment sales	7,144	6,319	23,360	19,304
Operating earnings by segment	43,137	45,949	140,827	139,149
Restructuring charges	(961)	0	(1,246)	(892)
Europe
Segment Reporting Information [Line Items]
Net sales by segment to unaffiliated customers	224,931	186,069	621,864	563,765
Intersegment sales	29,989	22,086	97,369	66,186
Operating earnings by segment	23,794	20,435	54,888	57,268
Restructuring charges	(848)	1,153	(3,172)	(3,663)
Intersegment sales	0	(17,000)	0	(17,000)
Inventory adjustment relating to exit activities - EMEA	0	502	0	(2,157)
Asia
Segment Reporting Information [Line Items]
Net sales by segment to unaffiliated customers	80,767	63,656	227,641	208,067
Intersegment sales	6,213	6,285	16,524	18,070
Operating earnings by segment	3,318	3,984	10,744	11,741
Restructuring charges	$ 0	$ 0	$ 0	$ (482)

Subsequent Events - (Details)

Subsequent Events - (Details) - USD ($)	Feb. 07, 2018	Jan. 09, 2018	Jan. 09, 2018	Dec. 31, 2017
Subsequent Event
Subsequent Event [Line Items]
Common stock dividends (in dollars per share)	$ 0.175
ASR Agreement
Subsequent Event [Line Items]
Stock repurchase program, authorized amount				$ 100,000
ASR Agreement | Subsequent Event
Subsequent Event [Line Items]
Shares repurchased during period (in shares)		1,495,714	216,738
Total cash investment		$ 100,000	$ 100,000
Total cash investment per share (usd per share)			$ 66.86