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Business Segment and Geographic Information - Additional Information (Detail) (USD $) | 12 Months Ended
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Mar. 31, 2015 Segment | Mar. 31, 2014 | Mar. 31, 2013
Segment Reporting Information [Line Items] |  |  |
Number of reportable business segments | 2 us-gaap_NumberOfReportableSegments |  |
Stock-based compensation expense | $ 5,936,000 us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue | $ 10,696,000 us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue | $ 8,138,000 us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
Restructuring and impairment charges | 5,400,000 us-gaap_RestructuringCostsAndAssetImpairmentCharges | 3,000,000 us-gaap_RestructuringCostsAndAssetImpairmentCharges | 7,900,000 us-gaap_RestructuringCostsAndAssetImpairmentCharges
Loss contingency accrual |  |  | $ 1,800,000 us-gaap_LossContingencyAccrualAtCarryingValue
Geographic Concentration Risk | Sales Revenue, Net | Outside The United States |  |  |
Segment Reporting Information [Line Items] |  |  |
Risk percentage | 86.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueNetMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_GeographicConcentrationRiskMember / us-gaap_StatementGeographicalAxis = amsc_OutsideUnitedStatesMember | 87.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueNetMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_GeographicConcentrationRiskMember / us-gaap_StatementGeographicalAxis = amsc_OutsideUnitedStatesMember | 85.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueNetMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_GeographicConcentrationRiskMember / us-gaap_StatementGeographicalAxis = amsc_OutsideUnitedStatesMember
Customer Concentration Risk | Sales Revenue, Net | Inox Wind Limited |  |  |
Segment Reporting Information [Line Items] |  |  |
Risk percentage | 56.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueNetMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = amsc_InoxWindLimitedMember | 31.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueNetMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = amsc_InoxWindLimitedMember | 19.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueNetMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = amsc_InoxWindLimitedMember
Customer Concentration Risk | Sales Revenue, Net | JCNE |  |  |
Segment Reporting Information [Line Items] |  |  |
Risk percentage |  | 18.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueNetMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = amsc_BeijingJingchengNewEnergyCompanyLimitedMember | 13.00%us-gaap_ConcentrationRiskPercentage1 / us-gaap_ConcentrationRiskByBenchmarkAxis = us-gaap_SalesRevenueNetMember / us-gaap_ConcentrationRiskByTypeAxis = us-gaap_CustomerConcentrationRiskMember / us-gaap_MajorCustomersAxis = amsc_BeijingJingchengNewEnergyCompanyLimitedMember
Minimum |  |  |
Segment Reporting Information [Line Items] |  |  |
Megawatts of drive trains and power ratings | 2 amsc_BusinessSegmentsPowerOfWindTurbines / us-gaap_RangeAxis = us-gaap_MinimumMember |  |

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- Definition Business segments power of wind turbines. + References No definition available. + Details
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- Definition This element represents the amount of recognized equity-based compensation during the period, that is, the amount recognized as expense in the income statement (or as asset if compensation is capitalized). Alternate captions include the words "stock-based compensation". + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 35 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415241&loc=d3e4534-113899 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 20 -Section 55 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=32706628&loc=d3e11149-113907 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 20 -Section 55 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=32706628&loc=d3e11178-113907 + Details
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- Definition For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 21 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13537-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6404-108592 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13531-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6351-108592 + Details
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- Definition Amount of loss contingency liability. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349 + Details
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- Definition Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements. + References No definition available. + Details
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- Definition Amount, after cash payment, of expenses associated with exit or disposal activities pursuant to an authorized plan and expenses resulting from the write-down of assets. Excludes expenses related to a business combination, a discontinued operation or an asset retirement obligation. + 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 + Details
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