Annual and transition report of foreign private issuers pursuant to Section 13 or 15(d)

Stock-Based Compensation - Restricted Stock Activity (Detail)

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Stock-Based Compensation - Restricted Stock Activity (Detail) (USD $)
12 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Compensation Related Costs Share Based Payments Disclosure [Line Items]    
Non-vested shares, Beginning balance 3,677,511 5,112,095
Granted, Shares 1,415,605 1,303,209
Vested, Shares (846,415) (2,527,601)
Forfeited, Shares (242,333) (210,192)
Non-vested shares, Ending balance 4,004,368 3,677,511
Weighted Average Fair Value at Grant Date, Non-vested, Beginning balance $ 5.57 $ 4.52
Weighted Average Fair Value at Grant Date, Granted $ 8.41 $ 4.92
Weighted Average Fair Value at Grant Date, Vested $ 7.13 $ 3.13
Weighted Average Fair Value at Grant Date, Forfeited $ 5.96 $ 5.35
Weighted Average Fair Value at Grant Date, Non-vested, Ending balance $ 6.13 $ 5.57