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