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Warrants and Derivative Liabilities - Schedule of Assumptions Used to Calculate the Fair Value of Warrants (Detail) (USD $) In Millions, unless otherwise specified | 0 Months Ended | 3 Months Ended | 0 Months Ended | 3 Months Ended | 0 Months Ended
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Apr. 04, 2012 | Dec. 31, 2013 | Sep. 30, 2013 | Jun. 30, 2013 | Mar. 31, 2013 | Dec. 31, 2012 | Sep. 30, 2012 | Jun. 30, 2012 | Dec. 20, 2012 | Mar. 31, 2015 | Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Oct. 09, 2013 | Dec. 19, 2014 | Jun. 05, 2012 | Nov. 15, 2013 | Nov. 13, 2014
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
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 |  |  |  |  |  |  |  |  |  |  |
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 |  |  |  |  |  |  |  |  |  |  |
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 |  |  |  |  |  |  |  |  |  |  |
Post Modification |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
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 |  |  |  |  |  |  |  |  |  |
Expected volatility |  |  |  |  |  |  |  |  | 72.50%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_RangeAxis = amsc_PostModificationMember |  |  |  |  |  |  |  |  |  |
Term (years) |  |  |  |  |  |  |  |  | 1 year 9 months 15 days |  |  |  |  |  |  |  |  |  |
Pre Modification |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
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 |  |  |  |  |  |  |  |  |  |
Expected volatility |  |  |  |  |  |  |  |  | 72.50%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_RangeAxis = amsc_PreModificationMember |  |  |  |  |  |  |  |  |  |
Term (years) |  |  |  |  |  |  |  |  | 1 year 9 months 15 days |  |  |  |  |  |  |  |  |  |
Senior Convertible Note Warrant |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk-free interest rate | 1.19%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 1.17%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 1.02%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 1.13%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 0.67%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 0.75%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 0.63%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 0.77%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember |  | 0.73%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 1.00%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 1.07%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 0.98%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 1.11%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember |  |  |  |  |
Expected volatility | 80.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 75.60%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 71.98%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 71.90%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 71.74%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 80.60%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 80.90%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 80.80%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember |  | 70.42%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 72.38%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 76.20%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 83.50%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 80.99%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember |  |  |  |  |
Term (years) | 5 years 6 months | 3 years 9 months 4 days | 4 years 4 days | 4 years 3 months 7 days | 4 years 6 months 4 days | 4 years 9 months 4 days | 5 years 4 days | 5 years 3 months 11 days |  | 2 years 6 months 4 days | 2 years 9 months 4 days | 3 years 4 days | 3 years 3 months 4 days | 3 years 6 months 4 days |  |  |  |  |
Fair value | 7.0 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 2.2 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 2.5 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 3.0 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 3.4 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 4.4 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 7.1 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | 8.6 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember |  | $ 0.3 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | $ 0.5 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | $ 1.5 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | $ 2.3 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember | $ 2.2 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember |  |  |  |  |
Senior Convertible Note Warrant | Post Modification |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk-free interest rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.05%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember / us-gaap_RangeAxis = amsc_PostModificationMember |  |  |  |
Expected volatility |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 71.45%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember / us-gaap_RangeAxis = amsc_PostModificationMember |  |  |  |
Term (years) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 years 11 months 27 days |  |  |  |
Fair value |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3.2 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember / us-gaap_RangeAxis = amsc_PostModificationMember |  |  |  |
Senior Convertible Note Warrant | Pre Modification |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk-free interest rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.05%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember / us-gaap_RangeAxis = amsc_PreModificationMember |  |  |  |
Expected volatility |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 71.45%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember / us-gaap_RangeAxis = amsc_PreModificationMember |  |  |  |
Term (years) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 years 11 months 27 days |  |  |  |
Fair value |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2.2 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorConvertibleNoteWarrantMember / us-gaap_RangeAxis = amsc_PreModificationMember |  |  |  |
Senior Secured Term Loan First Warrant |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk-free interest rate |  | 1.24%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 1.09%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 1.20%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 0.70%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 0.75%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 0.64%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 0.80%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember |  |  |  | 1.13%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 1.04%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 1.18%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember |  | 1.10%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 0.77%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember |  |
Expected volatility |  | 74.79%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 72.10%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 72.30%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 72.01%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 80.14%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 81.18%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 80.32%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember |  |  |  | 78.30%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 82.75%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 80.73%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember |  | 67.01%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 79.99%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember |  |
Term (years) |  | 3 years 11 months 5 days | 4 years 2 months 5 days | 4 years 5 months 5 days | 4 years 8 months 5 days | 4 years 11 months 5 days | 5 years 2 months 5 days | 5 years 5 months 9 days |  |  | 0 years | 3 years 2 months 5 days | 3 years 5 months 5 days | 3 years 8 months 5 days |  | 2 years 11 months 16 days | 5 years 6 months |  |
Fair value |  | 0.1 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 0.2 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 0.2 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 0.2 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 0.2 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 0.4 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 0.5 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember |  |  | 0 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 0.1 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 0.1 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 0.1 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember |  | 0.1 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember | 0.4 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember |  |
Senior Secured Term Loan First Warrant | Post Modification |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk-free interest rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.00%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember / us-gaap_RangeAxis = amsc_PostModificationMember |
Expected volatility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 72.64%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember / us-gaap_RangeAxis = amsc_PostModificationMember |
Term (years) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4 years 18 days |
Fair value |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.1 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember / us-gaap_RangeAxis = amsc_PostModificationMember |
Senior Secured Term Loan First Warrant | Pre Modification |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk-free interest rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.00%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember / us-gaap_RangeAxis = amsc_PreModificationMember |
Expected volatility |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 72.64%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember / us-gaap_RangeAxis = amsc_PreModificationMember |
Term (years) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4 years 18 days |
Fair value |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.1 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanFirstWarrantMember / us-gaap_RangeAxis = amsc_PreModificationMember |
Senior Secured Term Loan Second Warrant |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk-free interest rate |  | 1.89%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember |  |  |  |  |  |  |  |  |  | 1.65%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember | 1.57%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember | 1.76%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember |  | 1.65%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember |  | 1.55%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember |
Expected volatility |  | 80.37%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember |  |  |  |  |  |  |  |  |  | 78.10%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember | 80.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember | 79.73%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember |  | 71.82%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember |  | 76.97%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember |
Term (years) |  | 5 years 4 months 13 days |  |  |  |  |  |  |  |  | 0 years | 4 years 7 months 13 days | 4 years 10 months 13 days | 5 years 1 month 13 days |  | 4 years 4 months 28 days |  | 5 years 5 months 27 days |
Fair value |  | 0.3 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember |  |  |  |  |  |  |  |  | 0 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember | 0.2 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember | 0.3 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember | 0.3 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember |  | 0.1 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember |  | 0.3 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanSecondWarrantMember |
Senior Secured Term Loan New Warrant |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk-free interest rate |  |  |  |  |  |  |  |  |  | 1.41%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanNewWarrantMember | 1.73%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanNewWarrantMember |  |  |  |  | 1.74%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanNewWarrantMember |  |  |
Expected volatility |  |  |  |  |  |  |  |  |  | 74.60%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanNewWarrantMember | 77.43%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanNewWarrantMember |  |  |  |  | 70.26%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanNewWarrantMember |  |  |
Term (years) |  |  |  |  |  |  |  |  |  | 5 years 3 months | 5 years 6 months |  |  |  |  | 5 years 6 months 11 days |  |  |
Fair value |  |  |  |  |  |  |  |  |  | 0.2 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanNewWarrantMember | 0.2 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanNewWarrantMember |  |  |  |  | 0.2 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_SeniorSecuredTermLoanNewWarrantMember |  |  |
November 2014 Warrant |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk-free interest rate |  |  |  |  |  |  |  |  |  | 1.28%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_NovemberTwoThousandFourteenWarrantMember | 1.61%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_NovemberTwoThousandFourteenWarrantMember |  |  |  |  |  |  |  | 1.64%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_NovemberTwoThousandFourteenWarrantMember
Expected volatility |  |  |  |  |  |  |  |  |  | 75.96%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_NovemberTwoThousandFourteenWarrantMember | 78.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_NovemberTwoThousandFourteenWarrantMember |  |  |  |  |  |  |  | 72.86%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_ClassOfWarrantOrRightAxis = amsc_NovemberTwoThousandFourteenWarrantMember
Term (years) |  |  |  |  |  |  |  |  |  | 4 years 7 months 13 days | 4 years 10 months 13 days |  |  |  |  |  |  |  | 5 years
Fair value |  |  |  |  |  |  |  |  |  | $ 2.5 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_NovemberTwoThousandFourteenWarrantMember | $ 3.2 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_NovemberTwoThousandFourteenWarrantMember |  |  |  |  |  |  |  | $ 4.3 amsc_WarrantInstrumentsFairValueDisclosure / us-gaap_ClassOfWarrantOrRightAxis = amsc_NovemberTwoThousandFourteenWarrantMember

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- Definition Expected dividends to be paid to holders of the underlying shares or financial instruments (expressed as a percentage of the share or instrument's price). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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- Definition Period the instrument, asset or liability is expected to be outstanding, 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 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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- Definition Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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- Definition Risk-free interest rate assumption used in valuing an instrument. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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