Equity Method Investment, Percentage of Investment Sold

No definition available.

Name:	amsc_EquityMethodInvestmentPercentageofInvestmentSold
Namespace Prefix:	amsc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Equity method investments, number of commonly interconnected power grids.

+ References

No definition available.

+ Details

Name:	amsc_EquityMethodInvestmentsNumberOfCommonlyInterconnectedPowerGrids
Namespace Prefix:	amsc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

This element represents the aggregate cost of investments accounted for under the equity method of accounting.

+ 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 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

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=66902209&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 35
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e25351-111560

+ Details

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

- Definition

The cash inflow associated with the sale of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3179-108585

+ Details

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

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

- Details

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Namespace Prefix:
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- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
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Minority Investments - Additional Information (Detail) $ in Thousands	3 Months Ended				7 Months Ended
	Dec. 31, 2016 USD ($)	Jun. 30, 2016 USD ($) power_grid	Mar. 31, 2016 USD ($)	Jun. 30, 2015 USD ($)	Sep. 30, 2016 USD ($)
Schedule Of Equity Method Investments [Line Items]
Impairment of minority interest investment		$ 0		$ 746
Tres Amigas
Schedule Of Equity Method Investments [Line Items]
Number of commonly interconnected power grids \| power_grid		3
Minority investment, aggregate cost		$ 5,400
Impairment of minority interest investment				$ 700
Minority share investment proceeds			$ 300
Scenario, Forecast \| Tres Amigas
Schedule Of Equity Method Investments [Line Items]
Minority investment, percentage of investment sold					100.00%
Minority share investment proceeds	$ 300				$ 600