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Note 7 - Fair Value Measurements (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Oct. 01, 2020	Nov. 30, 2014
Debt Securities, Available-for-sale, Unrealized Gain (Loss), Total	$ 0	$ 0	$ (200)	$ 0
Class of Warrant or Right, Outstanding (in shares)	0		0
Hudson Warrant [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)		818,181		818,181		58,823
Northeast Power Systems, Inc (NEPSI) [Member]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High, Number of Shares (in shares)					1,000,000
Maximum [Member] | Certificates of Deposit [Member]
Marketable Securities, Realized Gain (Loss), Total			$ 100

X

- Definition

For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid in shares.

+ References

No definition available.

+ Details

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

X

- 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/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

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

X

- Definition

Number of warrants or rights outstanding.

+ References

No definition available.

+ Details

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

X

- Definition

Amount of unrealized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

No definition available.

+ Details

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

X

- Definition

Amount of realized gain (loss) on investment in marketable security, including other-than-temporary impairment (OTTI).

+ References

No definition available.

+ Details

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

X

- Details

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

X

- Details

Name:	us-gaap_BusinessAcquisitionAxis=amsc_NortheastPowerSystemsIncNEPSIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_CertificatesOfDepositMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: