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Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Inventory reserve	$ 1.4us-gaap_InventoryValuationReserves	$ 0.3us-gaap_InventoryValuationReserves
Benefit to cost of revenues	8.0amsc_CostOfRevenuesBenefitInventoriesPreviouslyWrittenDown	4.3amsc_CostOfRevenuesBenefitInventoriesPreviouslyWrittenDown	2.1amsc_CostOfRevenuesBenefitInventoriesPreviouslyWrittenDown
Impairment charge		0us-gaap_AssetImpairmentCharges	5.0us-gaap_AssetImpairmentCharges
Payments received from customers	0us-gaap_Revenues	3.7us-gaap_Revenues	3.4us-gaap_Revenues
Percentage of tax benefit likely to be realized upon ultimate settlement	50.00%amsc_PercentageOfTaxBenefitLikelyToBeRealizedUponUltimateSettlement
Repatriated amount	1.2us-gaap_ForeignEarningsRepatriated
Common equivalent shares not included in the calculation of diluted EPS	1,567,352us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	643,158us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1,072,584us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Net foreign currency transaction and hedging gains (losses)	2.8us-gaap_ForeignCurrencyTransactionGainLossBeforeTax	0.1us-gaap_ForeignCurrencyTransactionGainLossBeforeTax	1.0us-gaap_ForeignCurrencyTransactionGainLossBeforeTax
Loss contingency accrual			1.8us-gaap_LossContingencyAccrualAtCarryingValue
Ghodawat Energy Pvt Ltd
Reversed legal expenses	2.2us-gaap_LegalFees / dei_LegalEntityAxis = amsc_GhodawatEnergyPvtLtdMember
Foreign Earnings Repatriated
Federal and state deferred tax liability	0.4us-gaap_DeferredTaxLiabilitiesCurrent / us-gaap_IncomeTaxAuthorityAxis = amsc_ForeignEarningsRepatriatedMember
Blade Dynamics Ltd
Impairment charge	$ 3.5us-gaap_AssetImpairmentCharges / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = amsc_BladeDynamicsLtdMember	$ 1.3us-gaap_AssetImpairmentCharges / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = amsc_BladeDynamicsLtdMember
Maximum
Warranty period	3 years
Minimum
Warranty period	1 year
Credit Concentration Risk | Accounts Receivable | Inox Wind Limited
Risk percentage	56.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_AccountsReceivableMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CreditConcentrationRiskMember / us-gaap_MajorCustomersAxis = amsc_InoxWindLimitedMember	20.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_AccountsReceivableMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CreditConcentrationRiskMember / us-gaap_MajorCustomersAxis = amsc_InoxWindLimitedMember
Credit Concentration Risk | Accounts Receivable | Inox Wind Limited | Maximum
Risk percentage	56.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_AccountsReceivableMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CreditConcentrationRiskMember / us-gaap_MajorCustomersAxis = amsc_InoxWindLimitedMember / us-gaap_RangeAxis = us-gaap_MaximumMember
Credit Concentration Risk | Accounts Receivable | Inox Wind Limited | Minimum
Risk percentage	10.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_AccountsReceivableMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CreditConcentrationRiskMember / us-gaap_MajorCustomersAxis = amsc_InoxWindLimitedMember / us-gaap_RangeAxis = us-gaap_MinimumMember
Credit Concentration Risk | Accounts Receivable | CG Power Solutions UK Ltd
Risk percentage		14.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_AccountsReceivableMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CreditConcentrationRiskMember / us-gaap_MajorCustomersAxis = amsc_CGPowerSolutionsUKLtdMember
Credit Concentration Risk | Accounts Receivable | JINGCHENG New Energy
Risk percentage		13.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_AccountsReceivableMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CreditConcentrationRiskMember / us-gaap_MajorCustomersAxis = amsc_JINGCHENGNewEnergyMember

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