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Stockholders' Equity - Additional Information (Detail) (USD $) | 0 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Mar. 24, 2015 | Nov. 13, 2014 | Mar. 31, 2015 | Mar. 31, 2014 | Mar. 31, 2013 | Nov. 15, 2013
Stockholders Equity [Line Items] |  |  |  |  |  |
Weighted-average grant-date fair value of stock option awards granted |  |  | $ 10.18 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue | $ 16.20 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue | $ 25.60 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value |  |  | $ 0 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1 | $ 0 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1 | $ 0 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1 |
Shares, Granted |  |  | 332,782 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod |  |  |
Number of shares cancelled |  |  | 22,788 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod |  |  |
Stock-based compensation plans expired terms |  |  | May 02, 2007 |  |  |
Contractual life of options, in years |  |  | 10 years |  |  |
Vesting period of shares granted by option upon election to board |  |  | 2 years |  |  |
Compensation expense recognized |  |  | 100,000 us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense | 100,000 us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense | 100,000 us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense |
Common stock |  |  | 96,000 us-gaap_CommonStockValue | 79,000 us-gaap_CommonStockValue |  |
Proceeds From Issuance Of Common Stock |  | 9,100,000 us-gaap_ProceedsFromIssuanceOfCommonStock |  |  |  |
Common stock, shares issued |  |  | 9,624,275 us-gaap_CommonStockSharesIssued | 7,892,990 us-gaap_CommonStockSharesIssued |  |
Shares issued, price per share |  | $ 11.00 us-gaap_SaleOfStockPricePerShare |  |  |  |
Reverse stock split, description |  |  | adjusted to reflect our 1-for-10 reverse stock split |  |  |
Reverse stock split | 0.1 us-gaap_StockholdersEquityNoteStockSplitConversionRatio1 | 0.1 us-gaap_StockholdersEquityNoteStockSplitConversionRatio1 |  |  |  |
Common stock units offered |  | 909,090 us-gaap_CommonUnitIssued |  |  |  |
Number of warrants issued to purchase common stock |  | 818,181 amsc_NumberOfWarrantsIssuedToPurchaseCommonStock |  |  |  |
Warrants to purchase one share of common stock |  | 90.00%amsc_WarrantsToPurchaseOneShareOfCommonStock |  |  |  |
M L V And Co | At Market Sales Agreement |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Commission on sale of common stock under the ATM |  |  |  |  |  | 3.00%amsc_PercentageOnSaleOfStockConsiderationReceivedOnTransaction / us-gaap_ClassOfWarrantOrRightAxis = amsc_AtMarketSalesAgreementMember / dei_LegalEntityAxis = amsc_MLVAndCoMember
M L V And Co | Atm Arrangement |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Proceeds From Issuance Of Common Stock |  |  | 5,800,000 us-gaap_ProceedsFromIssuanceOfCommonStock / us-gaap_ClassOfWarrantOrRightAxis = amsc_AtmArrangementMember / dei_LegalEntityAxis = amsc_MLVAndCoMember | 7,500,000 us-gaap_ProceedsFromIssuanceOfCommonStock / us-gaap_ClassOfWarrantOrRightAxis = amsc_AtmArrangementMember / dei_LegalEntityAxis = amsc_MLVAndCoMember |  |
Common stock, shares issued |  |  | 375,000 us-gaap_CommonStockSharesIssued / us-gaap_ClassOfWarrantOrRightAxis = amsc_AtmArrangementMember / dei_LegalEntityAxis = amsc_MLVAndCoMember | 487,000 us-gaap_CommonStockSharesIssued / us-gaap_ClassOfWarrantOrRightAxis = amsc_AtmArrangementMember / dei_LegalEntityAxis = amsc_MLVAndCoMember |  |
Shares issued, price per share |  |  | $ 16.05 us-gaap_SaleOfStockPricePerShare / us-gaap_ClassOfWarrantOrRightAxis = amsc_AtmArrangementMember / dei_LegalEntityAxis = amsc_MLVAndCoMember | $ 16.24 us-gaap_SaleOfStockPricePerShare / us-gaap_ClassOfWarrantOrRightAxis = amsc_AtmArrangementMember / dei_LegalEntityAxis = amsc_MLVAndCoMember |  |
Maximum | M L V And Co | At Market Sales Agreement |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Common stock |  |  |  |  |  | 30,000,000 us-gaap_CommonStockValue / us-gaap_ClassOfWarrantOrRightAxis = amsc_AtMarketSalesAgreementMember / dei_LegalEntityAxis = amsc_MLVAndCoMember / us-gaap_RangeAxis = us-gaap_MaximumMember
Stock Options |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Unrecognized compensation cost for unvested employee stock-based compensation awards outstanding, net of forfeitures |  |  | 1,200,000 us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 2,000,000 us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |
Weighted-average period over which unrecognized compensation expense is expected to be recognized (years) |  |  | 2 years 8 months 12 days |  |  |
Stock Options | Minimum |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Vesting period, in years |  |  | 3 years |  |  |
Stock Options | Maximum |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Vesting period, in years |  |  | 5 years |  |  |
Restricted Stock and Stock Awards |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Unrecognized compensation cost for unvested employee stock-based compensation awards outstanding, net of forfeitures |  |  | 2,600,000 us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember | 1,800,000 us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember |  |
Weighted-average period over which unrecognized compensation expense is expected to be recognized (years) |  |  | 1 year 2 months 12 days |  |  |
Total fair value of restricted stock granted |  |  | 5,600,000 amsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember | 4,500,000 amsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember | 10,600,000 amsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember |
Total fair value of restricted stock granted for bonuses and severance |  |  |  | 500,000 amsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsBonusAndSeveranceGrantsFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember | 1,600,000 amsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsBonusAndSeveranceGrantsFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember |
Total fair value of restricted stock vested |  |  | 3,100,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember | 3,700,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember | 3,400,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember |
Total fair value of restricted stock granted for bonuses and severance |  |  |  | 500,000 amsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsBonusAndSeveranceStockVestedInPeriodFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember | 1,600,000 amsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsBonusAndSeveranceStockVestedInPeriodFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember |
Vesting period, in years |  |  | 3 years |  |  |
U.S. Treasury Rates | Minimum |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Stock-based compensation plans expired terms |  |  | 5 years |  |  |
U.S. Treasury Rates | Maximum |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Stock-based compensation plans expired terms |  |  | 7 years |  |  |
Performance-Based Restricted Stock |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Shares, Granted |  |  | 38,021 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = amsc_PerformanceBasedRestrictedStockMember | 40,201 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = amsc_PerformanceBasedRestrictedStockMember | 142,212 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = amsc_PerformanceBasedRestrictedStockMember |
Restricted Stock Units (RSUs) |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Number of shares cancelled |  |  | 10,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |  |  |
2007 Director Stock Option Plan |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Number of shares granted by option upon election to the board |  |  | 1,000 amsc_NumberOfSharesGrantedByOptionUponElectionToBoard / us-gaap_AwardTypeAxis = amsc_TwoThousandAndSevenDirectorPlanMember |  |  |
Number of shares awarded annually |  |  | 300 amsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAwardedAnnually / us-gaap_AwardTypeAxis = amsc_TwoThousandAndSevenDirectorPlanMember |  |  |
Grant date value of shares granted by option upon election to board |  |  | $ 40,000 amsc_GrantDateValueOfSharesGrantedByOptionUponElectionToBoard / us-gaap_AwardTypeAxis = amsc_TwoThousandAndSevenDirectorPlanMember |  |  |
Number of shares authorized for issuance under the plan |  |  | 64,700 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_AwardTypeAxis = amsc_TwoThousandAndSevenDirectorPlanMember |  |  |
2007 Stock Incentive Plan |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Number of shares authorized for issuance under the plan |  |  | 557,578 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_AwardTypeAxis = amsc_TwoThousandAndSevenPlanMember |  |  |
Employee Stock Purchase Plan |  |  |  |  |  |
Stockholders Equity [Line Items] |  |  |  |  |  |
Number of shares authorized for issuance under the plan |  |  | 16,708 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_AwardTypeAxis = amsc_EmployeeStockPurchasePlanMember |  |  |
Percentage of purchase discount |  |  | 15.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate / us-gaap_AwardTypeAxis = amsc_EmployeeStockPurchasePlanMember |  |  |
Common stock shares issued |  |  | 8,168 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod / us-gaap_AwardTypeAxis = amsc_EmployeeStockPurchasePlanMember |  |  |

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- Definition Discount rate from fair value on offering date that participants pay for shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Date the equity-based award expires, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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