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	2018
Document Fiscal Period Focus	Q3
Trading Symbol	ENS
Entity Registrant Name	EnerSys
Entity Central Index Key	0001289308
Current Fiscal Year End Date	--03-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		41,910,079