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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 | $ 13,200,000 us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost |
Excess tax deductions from stock option exercised | 52,400,000 us-gaap_DeferredTaxExpenseFromStockOptionsExercised |
Stock options exercised dates | March 31, 2006 through 2015 |
Repatriated amount | 1,200,000 us-gaap_ForeignEarningsRepatriated |
Minimum percentage of amount being realized upon ultimate settlement | 50.00%amsc_MinimumPercentageOfAmountBeingRealizedUponUltimateSettlement |
Uncertain tax positions | 0 us-gaap_LiabilityForUncertainTaxPositionsCurrent |
Unrecognized tax benefits that, if recognized, would result in a reduction of the Company's effective tax rate | 0 us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate | 1,100,000 us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate
Austria |  |
Net operating loss carryforwards | 51,500,000 us-gaap_OperatingLossCarryforwards / us-gaap_StatementGeographicalAxis = amsc_AustriaMember |
China |  |
Net operating loss carryforwards | 28,600,000 us-gaap_OperatingLossCarryforwards / us-gaap_StatementGeographicalAxis = country_CN |
ROMANIA |  |
Net operating loss carryforwards | 3,000,000 us-gaap_OperatingLossCarryforwards / us-gaap_StatementGeographicalAxis = country_RO |
Federal |  |
Net operating loss carryforwards | 760,400,000 us-gaap_OperatingLossCarryforwards / us-gaap_IncomeTaxAuthorityAxis = us-gaap_DomesticCountryMember |
Research and development and other tax credit carryforwards | 8,200,000 us-gaap_TaxCreditCarryforwardAmount / us-gaap_IncomeTaxAuthorityAxis = us-gaap_DomesticCountryMember |
State |  |
Net operating loss carryforwards | 185,500,000 us-gaap_OperatingLossCarryforwards / us-gaap_IncomeTaxAuthorityAxis = us-gaap_StateAndLocalJurisdictionMember |
Research and development and other tax credit carryforwards | 3,000,000 us-gaap_TaxCreditCarryforwardAmount / us-gaap_IncomeTaxAuthorityAxis = us-gaap_StateAndLocalJurisdictionMember |
Foreign Earnings Repatriated |  |
Federal and state deferred tax liability | 400,000 us-gaap_DeferredTaxLiabilitiesCurrent / us-gaap_IncomeTaxAuthorityAxis = amsc_ForeignEarningsRepatriatedMember |
Power Quality Systems, Inc. |  |
Net operating loss carryforwards | $ 3,700,000 us-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 |

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