Earnings Per Share - Weighted Average Common Shares Basic and Common Shares Diluted (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 30, 2018	Sep. 30, 2018	Jul. 01, 2018	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net earnings attributable to EnerSys stockholders	$ (1,523)	$ 27,305	$ 62,698	$ 48,636	$ 18,538	$ 48,417	$ 47,424	$ 45,860	$ 137,116	$ 160,239	$ 119,594
Basic (in shares)									42,411,834	42,335,023	42,612,036
Dilutive effect of:
Common shares from exercise and lapse of equity awards, net of shares assumed reacquired (in shares)									484,941	673,929	507,820
Diluted weighted-average number of common shares outstanding (in shares)									42,896,775	43,008,952	43,119,856
Basic earnings per common share attributable to EnerSys stockholders (usd per share)	$ (0.04)	$ 0.65	$ 1.48	$ 1.14	$ 0.43	$ 1.14	$ 1.13	$ 1.09	$ 3.23	$ 3.79	$ 2.81
Diluted earnings per common share attributable to EnerSys stockholders (usd per share)	$ (0.04)	$ 0.64	$ 1.47	$ 1.13	$ 0.42	$ 1.12	$ 1.11	$ 1.08	$ 3.20	$ 3.73	$ 2.77
Anti-dilutive equity awards not included in diluted weighted-average common shares (in shares)									698,546,000	355,728,000	59,482,000