Document and Entity Information - USD ($)	12 Months Ended
	Mar. 31, 2018	May 08, 2018	Sep. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	ABMD
Entity Registrant Name	ABIOMED INC
Entity Central Index Key	0000815094
Current Fiscal Year End Date	--03-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		44,477,837
Entity Public Float			$ 7,452,252,182