Class of Warrant or Right, Number of Warrants to Purchase One Share of Stock

No definition available.

Name:	amsc_ClassOfWarrantOrRightNumberOfWarrantsToPurchaseOneShareOfStock
Namespace Prefix:	amsc_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Gain (loss) in change of fair value of derivative instruments and warrants.

+ References

No definition available.

+ Details

Name:	amsc_GainLossInChangeOfFairValueOfDerivativeInstrumentsAndWarrants
Namespace Prefix:	amsc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Number of warrants issued to purchase common stock.

+ References

No definition available.

+ Details

Name:	amsc_NumberOfWarrantsIssuedToPurchaseCommonStock
Namespace Prefix:	amsc_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Purchase commitment issuance of warrants shares of common stock.

+ References

No definition available.

+ Details

Name:	amsc_PurchaseCommitmentIssuanceOfWarrantsSharesOfCommonStock
Namespace Prefix:	amsc_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Expiration date of warrants held.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column A

+ Details

Name:	invest_InvestmentWarrantsExpirationDate
Namespace Prefix:	invest_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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 common units issued of limited liability company (LLC).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70434-108055

+ Details

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

- Definition

Fair value of the assets less the liabilities of a derivative or group of derivatives.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=amsc_NovemberTwoThousandFourteenWarrantMember
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_FirstWarrantsMember
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:

Warrants and Derivative Liabilities - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
	Dec. 19, 2014	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2018	Nov. 13, 2014
Derivative [Line Items]
Change in fair value of warrants and contingent consideration		$ 282	$ 144	$ (182)	$ 1,069
November 2014 Warrant
Derivative [Line Items]
Warrants expiration date				Nov. 13, 2019
Common stock units offered (in shares)							909,090
Warrants to purchase one share of common stock (in shares)							0.9
Number of warrants issued to purchase common stock (in shares)							818,181
Sale of stock, price per share (in dollars per share)							$ 7.81
Change in fair value of warrants and contingent consideration		$ 300	$ 100	$ (200)	$ 1,000
Senior secured loan \| Hercules Technology Growth Capital \| First Warrant
Derivative [Line Items]
Number of shares received from warrants received to purchase common stock (in shares)				13,927
Senior secured loan \| Hercules Technology Growth Capital \| Second Warrant
Derivative [Line Items]
Number of shares received from warrants received to purchase common stock (in shares)				25,641
Senior secured loan \| Hercules Technology Growth Capital \| Hercules Warrants
Derivative [Line Items]
Number of shares received from warrants received to purchase common stock (in shares)	58,823
Warrant exercise price (in dollars per share)		$ 7.85		$ 7.85
Warrants expiration date				Jun. 30, 2020
Warrant fair value		$ 100		$ 100		$ 100