XML 46 R59.htm IDEA: XBRL DOCUMENT v2.4.1.9

Minority Investments - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2014	Mar. 31, 2014	Dec. 31, 2014	Mar. 31, 2014
Tres Amigas
Schedule Of Equity Method Investments [Line Items]
Number of commonly interconnected power grids			3amsc_EquityMethodInvestmentsNumberOfCommonlyInterconnectedPowerGrids / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = amsc_TresAmigasMember
Equity method investment, aggregate cost			$ 5,400,000us-gaap_EquityMethodInvestmentAggregateCost / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = amsc_TresAmigasMember
Percentage of ownership interest hold			26.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = amsc_TresAmigasMember
Blade Dynamics Ltd.
Schedule Of Equity Method Investments [Line Items]
Cost method investment, original cost			8,000,000us-gaap_CostMethodInvestmentsOriginalCost / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = amsc_BladeDynamicsLtdMember
Percentage of ownership interest hold			12.00%us-gaap_MinorityInterestOwnershipPercentageByParent / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = amsc_BladeDynamicsLtdMember
Impairment charge on investment	$ 3,500,000us-gaap_ImpairmentOfInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = amsc_BladeDynamicsLtdMember	$ 1,300,000us-gaap_ImpairmentOfInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = amsc_BladeDynamicsLtdMember	$ 3,464,000us-gaap_ImpairmentOfInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = amsc_BladeDynamicsLtdMember	$ 1,300,000us-gaap_ImpairmentOfInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = amsc_BladeDynamicsLtdMember

X

- 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

X

- Definition

Original amount of cost-method investments at the acquisition date.

+ References

No definition available.

+ Details

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

X

- 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



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 12

-Article 5

+ Details

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

X

- Definition

The percentage of ownership of common stock or equity participation in the investee 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 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- 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=31042434&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

X

- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

Name:	us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Details

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

X

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=amsc_BladeDynamicsLtdMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=amsc_TresAmigasMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: