v2.4.0.6

Summary of Significant Accounting Policies - Additional Information (Detail) In Thousands, except Share data, unless otherwise specified	12 Months Ended						12 Months Ended
	Mar. 31, 2013 USD ($)	Mar. 31, 2012 USD ($)	Mar. 31, 2013 2011 Senior Secured Revolving Credit Facility USD ($)	Mar. 31, 2013 China Term Loan due 2017 CNY	Mar. 31, 2013 India Term Loan due 2017 INR	Mar. 31, 2013 Senior Unsecured 3.375% Convertible Notes Due 2038 USD ($)	Mar. 31, 2013 Restricted Stock and Restricted Stock Units	Mar. 31, 2013 Minimum	Mar. 31, 2013 Minimum Reserve Power Batteries	Mar. 31, 2013 Minimum Motive Power Batteries	Mar. 31, 2013 Minimum Land, Buildings and Improvements	Mar. 31, 2013 Minimum Machinery and Equipment	Mar. 31, 2013 Maximum	Mar. 31, 2013 Maximum Reserve Power Batteries	Mar. 31, 2013 Maximum Motive Power Batteries	Mar. 31, 2013 Maximum Land, Buildings and Improvements	Mar. 31, 2013 Maximum Machinery and Equipment
Summary Of Significant Accounting Policies [Line Items]
Percentage of investment ownership, consolidated								50.00%
Percentage of investment ownership, equity method								20.00%					50.00%
Percentage of investment ownership, cost method													20.00%
Product warranty for a period									1 year	1 year				20 years	7 years
Cash and cash equivalents include all highly liquid investments with an original maturity, when purchased, in months	3 months
Property, plant, and equipment, useful life											10 years	3 years				33 years	15 years
Estimated useful lives of finite-lived assets								3 years					20 years
Fair value of Company's new senior secured revolving credit facility			$ 350,000	75,000	273,780
Convertible Notes	$ 172,500	$ 172,500				$ 172,500
Interest rate of debt instrument						3.375%
Recognizes the largest amount of the benefit that is greater realized upon ultimate settlement, percentage	50.00%
Market share units converted into common stock for each unit								0					2
Percentage of restricted stock units granted, vested per year							25.00%
Vesting period, in years							4 years

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Cash and cash equivalents include all highly liquid investments with an original maturity, when purchased

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Cost Method Investment, Ownership Percentage

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Percentage Of Ownership Interests

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Product warranty for a period

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The number of shares converted in a noncash (or part noncash) transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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Interest rate stated in the contractual debt agreement.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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