Document and Entity Information - shares	6 Months Ended
	Oct. 02, 2016	Nov. 07, 2016
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Oct. 02, 2016
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q2
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		43,430,129