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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