XML 78 R66.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Warrants and Derivative Liabilities - Schedule of Assumptions Used to Calculate the Fair Value of Exchanged Warrants (Detail) - November 2014 Warrant $ in Millions | Sep. 30, 2018 USD ($) | Jun. 30, 2018 USD ($) | Mar. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Sep. 30, 2017 USD ($) | Jun. 30, 2017 USD ($) | Mar. 31, 2017 USD ($)
--- | --- | --- | --- | --- | --- | --- | ---
Derivative [Line Items] |  |  |  |  |  |  |
Fair value | $ 1.3 | $ 1.6 | $ 1.1 | $ 0.4 | $ 0.8 | $ 0.9 | $ 1.8
Risk-free interest rate |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |
Measurement inputs | 0.0262 | 0.0240 | 0.0220 | 0.0187 | 0.0149 | 0.0144 | 0.0141
Expected annual dividend yield |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |
Measurement inputs | 0 | 0 | 0 | 0 | 0 | 0 | 0
Expected volatility |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |
Measurement inputs | 0.6366 | 0.6740 | 0.6586 | 0.6586 | 0.6564 | 0.6721 | 0.6653
Term (years) |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |
Term (years) | 1 year 1 month 13 days | 1 year 4 months 13 days | 1 year 7 months 13 days | 1 year 10 months 13 days | 2 years 1 month 13 days | 2 years 4 months 13 days | 2 years 7 months 13 days

X
- 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

X
- Definition Value of outstanding derivative securities that permit the holder the right to purchase securities (usually equity) from the issuer at a specified price. + 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)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
Name: | us-gaap_WarrantsAndRightsOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Value of input used to measure outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258 + Details
Name: | us-gaap_WarrantsAndRightsOutstandingMeasurementInput
Namespace Prefix: | us-gaap_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Period between issuance and expiration of outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258 + Details
Name: | us-gaap_WarrantsAndRightsOutstandingTerm
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_ClassOfWarrantOrRightAxis=amsc_NovemberTwoThousandFourteenWarrantMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputRiskFreeInterestRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputExpectedDividendRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputPriceVolatilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputExpectedTermMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |