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Fair Value Measurements - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2014	Mar. 31, 2014	Dec. 31, 2014	Mar. 31, 2014
Blade Dynamics Ltd.
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment charge on investment	$ 3,500,000us-gaap_ImpairmentOfInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = amsc_BladeDynamicsLtdMember	$ 1,300,000us-gaap_ImpairmentOfInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = amsc_BladeDynamicsLtdMember	$ 3,464,000us-gaap_ImpairmentOfInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = amsc_BladeDynamicsLtdMember	$ 1,300,000us-gaap_ImpairmentOfInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = amsc_BladeDynamicsLtdMember
Convertible Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt, face amount		$ 25,000,000us-gaap_DebtInstrumentFaceAmount / us-gaap_ShortTermDebtTypeAxis = us-gaap_ConvertibleNotesPayableMember		$ 25,000,000us-gaap_DebtInstrumentFaceAmount / us-gaap_ShortTermDebtTypeAxis = us-gaap_ConvertibleNotesPayableMember
Debt Instrument, Interest Rate, Stated Percentage		7.00%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_ShortTermDebtTypeAxis = us-gaap_ConvertibleNotesPayableMember		7.00%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_ShortTermDebtTypeAxis = us-gaap_ConvertibleNotesPayableMember

X

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5



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The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

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