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Business Segments Power Of Wind Turbines

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Entity wide revenue geographical region percentage.

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Represents the number of customers.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Percentage of revenue generated from a single external customer that accounts for 10 percent or more of an entity's revenues.

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The carrying amount as of the balance sheet date of the combined total of loss contingency liabilities.

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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.

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Adjustment to remove noncash portion of restructuring costs and impairment charges.

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Business Segment And Geographic Information (Narrative) (Details) (USD $)	12 Months Ended
	Mar. 31, 2013 MW segment customer	Mar. 31, 2012 customer	Mar. 31, 2011
Segment Reporting Information [Line Items]
Number of reportable business segments	2
Megawatts of drive trains and power ratings	10
Stock-based compensation expense	$ 8,138,000	$ 9,864,000	$ 13,412,000
Restructuring and impairment charges	7,900,000	9,200,000
Loss contingency accrual	1,800,000
Write-off of advanced payment to The Switch		$ 20,551,000
Number of customers	2	2
Inox Wind [Member]
Segment Reporting Information [Line Items]
Percentage of total revenue, by customer	19.00%	18.00%
JCNE [Member]
Segment Reporting Information [Line Items]
Percentage of total revenue, by customer	13.00%
Doosan Heavy Industries [Member]
Segment Reporting Information [Line Items]
Percentage of total revenue, by customer		11.00%
Sinovel [Member]
Segment Reporting Information [Line Items]
Percentage of total revenue, by customer			68.00%
Outside The United States [Member]
Segment Reporting Information [Line Items]
Percentage of total revenue, by geographical region	85.00%	72.00%	93.00%