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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: |