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Income Taxes - Additional Information (Detail) (USD $)
 12 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Deferred tax asset reflecting the benefit of deductions from the exercise of stock options $ 13,200,000us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost  
Excess tax deductions from stock option exercised 52,400,000us-gaap_DeferredTaxExpenseFromStockOptionsExercised  
Stock options exercised dates March 31, 2006 through 2015  
Repatriated amount 1,200,000us-gaap_ForeignEarningsRepatriated  
Minimum percentage of amount being realized upon ultimate settlement 50.00%amsc_MinimumPercentageOfAmountBeingRealizedUponUltimateSettlement  
Uncertain tax positions 0us-gaap_LiabilityForUncertainTaxPositionsCurrent  
Unrecognized tax benefits that, if recognized, would result in a reduction of the Company's effective tax rate 0us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate 1,100,000us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate
Austria    
Net operating loss carryforwards 51,500,000us-gaap_OperatingLossCarryforwards
/ us-gaap_StatementGeographicalAxis
= amsc_AustriaMember		  
China    
Net operating loss carryforwards 28,600,000us-gaap_OperatingLossCarryforwards
/ us-gaap_StatementGeographicalAxis
= country_CN		  
ROMANIA    
Net operating loss carryforwards 3,000,000us-gaap_OperatingLossCarryforwards
/ us-gaap_StatementGeographicalAxis
= country_RO		  
Federal    
Net operating loss carryforwards 760,400,000us-gaap_OperatingLossCarryforwards
/ us-gaap_IncomeTaxAuthorityAxis
= us-gaap_DomesticCountryMember		  
Research and development and other tax credit carryforwards 8,200,000us-gaap_TaxCreditCarryforwardAmount
/ us-gaap_IncomeTaxAuthorityAxis
= us-gaap_DomesticCountryMember		  
State    
Net operating loss carryforwards 185,500,000us-gaap_OperatingLossCarryforwards
/ us-gaap_IncomeTaxAuthorityAxis
= us-gaap_StateAndLocalJurisdictionMember		  
Research and development and other tax credit carryforwards 3,000,000us-gaap_TaxCreditCarryforwardAmount
/ us-gaap_IncomeTaxAuthorityAxis
= us-gaap_StateAndLocalJurisdictionMember		  
Foreign Earnings Repatriated    
Federal and state deferred tax liability 400,000us-gaap_DeferredTaxLiabilitiesCurrent
/ us-gaap_IncomeTaxAuthorityAxis
= amsc_ForeignEarningsRepatriatedMember		  
Power Quality Systems, Inc.    
Net operating loss carryforwards $ 3,700,000us-gaap_OperatingLossCarryforwards
/ us-gaap_ProductOrServiceAxis
= amsc_PowerQualitySystemsIncMember		  
Maximum    
Operating loss carryforwards expiration years Mar. 31, 2035  
Expiration of other tax credit carryforwards Mar. 31, 2035  
Maximum | Austria    
Income tax examination years 2015  
Maximum | China    
Income tax examination years 2014  
Maximum | ROMANIA    
Income tax examination years 2015  
Maximum | U.S    
Income tax examination years 2015  
Minimum    
Operating loss carryforwards expiration years Mar. 31, 2016  
Expiration of other tax credit carryforwards Mar. 31, 2016  
Minimum | Austria    
Income tax examination years 2012  
Minimum | China    
Income tax examination years 2008  
Minimum | ROMANIA    
Income tax examination years 2014  
Minimum | U.S    
Income tax examination years 1995