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Warrants and Derivative Liabilities - Schedule of Fair Value Assumptions Used to Calculate Value of Convertible Note Derivative Feature (Detail) (USD $) | 0 Months Ended | 3 Months Ended | 12 Months Ended | 0 Months Ended
--- | --- | --- | --- | ---
Apr. 04, 2012 | Dec. 31, 2013 | Sep. 30, 2013 | Jun. 30, 2013 | Mar. 31, 2013 | Dec. 31, 2012 | Sep. 30, 2012 | Jun. 30, 2012 | Mar. 31, 2015 | Dec. 20, 2012
Combined principal balances of the term loans | $ 25,000,000 us-gaap_DebtInstrumentCarryingAmount | $ 10,411,000 us-gaap_DebtInstrumentCarryingAmount | $ 10,411,000 us-gaap_DebtInstrumentCarryingAmount | $ 14,389,000 us-gaap_DebtInstrumentCarryingAmount | $ 15,380,000 us-gaap_DebtInstrumentCarryingAmount | $ 20,944,000 us-gaap_DebtInstrumentCarryingAmount | $ 24,074,000 us-gaap_DebtInstrumentCarryingAmount | $ 25,000,000 us-gaap_DebtInstrumentCarryingAmount |  |
Stock price | $ 39.70 us-gaap_SharePrice | $ 16.40 us-gaap_SharePrice | $ 23.40 us-gaap_SharePrice | $ 26.40 us-gaap_SharePrice | $ 26.70 us-gaap_SharePrice | $ 26.20 us-gaap_SharePrice | $ 41.50 us-gaap_SharePrice | $ 46.80 us-gaap_SharePrice |  |
Percentage volume condition met | 85.90%amsc_PercentageVolumeConditionMet | 87.20%amsc_PercentageVolumeConditionMet | 80.20%amsc_PercentageVolumeConditionMet | 87.50%amsc_PercentageVolumeConditionMet | 80.50%amsc_PercentageVolumeConditionMet | 94.50%amsc_PercentageVolumeConditionMet | 51.00%amsc_PercentageVolumeConditionMet | 75.20%amsc_PercentageVolumeConditionMet |  |
Expected volatility | 75.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate | 68.63%us-gaap_FairValueAssumptionsExpectedVolatilityRate | 66.26%us-gaap_FairValueAssumptionsExpectedVolatilityRate | 65.80%us-gaap_FairValueAssumptionsExpectedVolatilityRate | 66.91%us-gaap_FairValueAssumptionsExpectedVolatilityRate | 73.50%us-gaap_FairValueAssumptionsExpectedVolatilityRate | 70.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate | 71.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate |  |
Risk-free interest rate | 0.44%us-gaap_FairValueAssumptionsRiskFreeInterestRate | 0.12%us-gaap_FairValueAssumptionsRiskFreeInterestRate | 0.10%us-gaap_FairValueAssumptionsRiskFreeInterestRate | 0.21%us-gaap_FairValueAssumptionsRiskFreeInterestRate | 0.20%us-gaap_FairValueAssumptionsRiskFreeInterestRate | 0.23%us-gaap_FairValueAssumptionsRiskFreeInterestRate | 0.23%us-gaap_FairValueAssumptionsRiskFreeInterestRate | 0.33%us-gaap_FairValueAssumptionsRiskFreeInterestRate |  |
Expected annual dividend yield | 15.00%us-gaap_FairValueAssumptionsExpectedDividendRate | 16.50%us-gaap_FairValueAssumptionsExpectedDividendRate | 15.50%us-gaap_FairValueAssumptionsExpectedDividendRate | 16.70%us-gaap_FairValueAssumptionsExpectedDividendRate | 16.50%us-gaap_FairValueAssumptionsExpectedDividendRate | 16.50%us-gaap_FairValueAssumptionsExpectedDividendRate | 15.00%us-gaap_FairValueAssumptionsExpectedDividendRate | 16.00%us-gaap_FairValueAssumptionsExpectedDividendRate |  |
Recovery rate | 30.00%amsc_FairValueAssumptionsRecoveryRate | 35.00%amsc_FairValueAssumptionsRecoveryRate | 35.00%amsc_FairValueAssumptionsRecoveryRate | 37.00%amsc_FairValueAssumptionsRecoveryRate | 30.00%amsc_FairValueAssumptionsRecoveryRate | 30.00%amsc_FairValueAssumptionsRecoveryRate | 30.00%amsc_FairValueAssumptionsRecoveryRate | 30.00%amsc_FairValueAssumptionsRecoveryRate |  |
Redeemable |  |  |  |  |  |  |  |  | yes |
Term (years) | 2 years 6 months | 9 months | 1 year | 1 year 3 months 4 days | 1 year 6 months 4 days | 1 year 9 months 4 days | 2 years 4 days | 2 years 3 months 11 days |  |
Dilution effect |  |  |  |  |  |  |  |  | yes |
Derivative Liability | 3,800,000 us-gaap_DerivativeLiabilities |  | 200,000 us-gaap_DerivativeLiabilities | 500,000 us-gaap_DerivativeLiabilities | 500,000 us-gaap_DerivativeLiabilities | 1,000,000 us-gaap_DerivativeLiabilities | 2,800,000 us-gaap_DerivativeLiabilities | 4,500,000 us-gaap_DerivativeLiabilities |  |
Fair value as a percent of par | 15.10%amsc_ConvertibleNotesFairValueAsPercentageOfParValue | 0.02%amsc_ConvertibleNotesFairValueAsPercentageOfParValue | 0.70%amsc_ConvertibleNotesFairValueAsPercentageOfParValue | 3.30%amsc_ConvertibleNotesFairValueAsPercentageOfParValue | 3.40%amsc_ConvertibleNotesFairValueAsPercentageOfParValue | 4.90%amsc_ConvertibleNotesFairValueAsPercentageOfParValue | 11.40%amsc_ConvertibleNotesFairValueAsPercentageOfParValue | 17.90%amsc_ConvertibleNotesFairValueAsPercentageOfParValue |  |
Post Modification |  |  |  |  |  |  |  |  |  |
Combined principal balances of the term loans |  |  |  |  |  |  |  |  |  | 20,944,000 us-gaap_DebtInstrumentCarryingAmount / us-gaap_RangeAxis = amsc_PostModificationMember
Stock price |  |  |  |  |  |  |  |  |  | $ 29.50 us-gaap_SharePrice / us-gaap_RangeAxis = amsc_PostModificationMember
Percentage volume condition met |  |  |  |  |  |  |  |  |  | 94.90%amsc_PercentageVolumeConditionMet / us-gaap_RangeAxis = amsc_PostModificationMember
Expected volatility |  |  |  |  |  |  |  |  |  | 72.50%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_RangeAxis = amsc_PostModificationMember
Risk-free interest rate |  |  |  |  |  |  |  |  |  | 0.25%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_RangeAxis = amsc_PostModificationMember
Expected annual dividend yield |  |  |  |  |  |  |  |  |  | 16.50%us-gaap_FairValueAssumptionsExpectedDividendRate / us-gaap_RangeAxis = amsc_PostModificationMember
Recovery rate |  |  |  |  |  |  |  |  |  | 30.00%amsc_FairValueAssumptionsRecoveryRate / us-gaap_RangeAxis = amsc_PostModificationMember
Redeemable |  |  |  |  |  |  |  |  | yes |
Term (years) |  |  |  |  |  |  |  |  |  | 1 year 9 months 15 days
Dilution effect |  |  |  |  |  |  |  |  | yes |
Derivative Liability |  |  |  |  |  |  |  |  |  | 1,500,000 us-gaap_DerivativeLiabilities / us-gaap_RangeAxis = amsc_PostModificationMember
Fair value as a percent of par |  |  |  |  |  |  |  |  |  | 7.10%amsc_ConvertibleNotesFairValueAsPercentageOfParValue / us-gaap_RangeAxis = amsc_PostModificationMember
Pre Modification |  |  |  |  |  |  |  |  |  |
Combined principal balances of the term loans |  |  |  |  |  |  |  |  |  | 24,074,000 us-gaap_DebtInstrumentCarryingAmount / us-gaap_RangeAxis = amsc_PreModificationMember
Stock price |  |  |  |  |  |  |  |  |  | $ 29.50 us-gaap_SharePrice / us-gaap_RangeAxis = amsc_PreModificationMember
Percentage volume condition met |  |  |  |  |  |  |  |  |  | 28.60%amsc_PercentageVolumeConditionMet / us-gaap_RangeAxis = amsc_PreModificationMember
Expected volatility |  |  |  |  |  |  |  |  |  | 72.50%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_RangeAxis = amsc_PreModificationMember
Risk-free interest rate |  |  |  |  |  |  |  |  |  | 0.25%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_RangeAxis = amsc_PreModificationMember
Expected annual dividend yield |  |  |  |  |  |  |  |  |  | 16.50%us-gaap_FairValueAssumptionsExpectedDividendRate / us-gaap_RangeAxis = amsc_PreModificationMember
Recovery rate |  |  |  |  |  |  |  |  |  | 30.00%amsc_FairValueAssumptionsRecoveryRate / us-gaap_RangeAxis = amsc_PreModificationMember
Redeemable |  |  |  |  |  |  |  |  | yes |
Term (years) |  |  |  |  |  |  |  |  |  | 1 year 9 months 15 days
Dilution effect |  |  |  |  |  |  |  |  | yes |
Derivative Liability |  |  |  |  |  |  |  |  |  | $ 900,000 us-gaap_DerivativeLiabilities / us-gaap_RangeAxis = amsc_PreModificationMember
Fair value as a percent of par |  |  |  |  |  |  |  |  |  | 3.90%amsc_ConvertibleNotesFairValueAsPercentageOfParValue / us-gaap_RangeAxis = amsc_PreModificationMember

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- Definition Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 + Details
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- Definition Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13433-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13495-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226008-175313 + Details
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