Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

Name:	us-gaap_AmortizationOfDebtDiscountPremium
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(2))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- 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 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

Reference 1: 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(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: 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(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of unamortized debt discount (premium) and debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

+ Details

Name:	us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of the cost of borrowed funds accounted for as interest expense for debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

Name:	us-gaap_InterestExpenseDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

No definition available.

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Value of preferred stock and warrants for common stock issued.

+ References

No definition available.

+ Details

Name:	us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=amsc_FIrstWarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=amsc_HerculesTechnologyGrowthCapitalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=amsc_SecondWarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=amsc_HerculesWarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=amsc_TermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=amsc_TermLoanBMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=amsc_TermLoanCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt - Additional Information (Detail) - USD ($)		3 Months Ended
Debt - Additional Information (Detail) - USD ($)	Dec. 19, 2014	Jun. 30, 2017	Jun. 30, 2016	Mar. 17, 2017	Mar. 16, 2017
FIrst Warrants \| Senior secured loan \| Hercules Technology Growth Capital
Debt Instrument [Line Items]
Number of shares received from warrants received to purchase common stock (in shares)	13,927
Fair value of warrants issued	$ 400,000
Second Warrants \| Senior secured loan \| Hercules Technology Growth Capital
Debt Instrument [Line Items]
Number of shares received from warrants received to purchase common stock (in shares)	25,641
Fair value of warrants issued	$ 200,000
Hercules Warrants \| Senior secured loan \| Hercules Technology Growth Capital
Debt Instrument [Line Items]
Number of shares received from warrants received to purchase common stock (in shares)	58,823
Warrant exercise price (in dollars per share)	$ 11.00	$ 8.02
Term Loan
Debt Instrument [Line Items]
Interest expense, debt (less than $0.1 million in three months 2017)			$ 200,000
Term Loan \| Senior secured loan
Debt Instrument [Line Items]
Interest expense, debt (less than $0.1 million in three months 2017)		$ 100,000
Term Loan B \| Senior secured loan
Debt Instrument [Line Items]
Non-cash interest expense amortization of debt discount (less than $0.1 million each for Term Loan B and Term Loan C)			100,000
Term Loan B \| Hercules Warrants \| Senior secured loan \| Hercules Technology Growth Capital
Debt Instrument [Line Items]
Non-cash interest expense amortization of debt discount (less than $0.1 million each for Term Loan B and Term Loan C)			100,000
Term Loan C \| Senior secured loan
Debt Instrument [Line Items]
Non-cash interest expense amortization of debt discount (less than $0.1 million each for Term Loan B and Term Loan C)		$ 100,000	100,000
Term Loan C \| Senior secured loan \| Hercules Technology Growth Capital
Debt Instrument [Line Items]
Debt, face amount	$ 1,500,000.0
Net proceeds from debt	1,400,000
Interest rate, stated percentage				11.25%	11.00%
Debt instrument, maturity date		Jun. 01, 2017
Term Loan C \| Hercules Warrants \| Senior secured loan \| Hercules Technology Growth Capital
Debt Instrument [Line Items]
Unamortized discount (premium) and debt issuance costs	$ 300,000
Non-cash interest expense amortization of debt discount (less than $0.1 million each for Term Loan B and Term Loan C)		$ 100,000	$ 100,000