Document and Entity Information (USD $) In Millions, except Share data	12 Months Ended
	Mar. 31, 2011	Sep. 15, 2011	Sep. 30, 2010
Document and Entity Information
Document Type	10-K
Amendment Flag	false
Document Period End Date	Mar. 31, 2011
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	FY
Entity Registrant Name	AMERICAN SUPERCONDUCTOR CORP /DE/
Entity Central Index Key	0000880807
Current Fiscal Year End Date	--03-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		50,868,708
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Public Float			$ 1,391.9