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