Schedule of Fair Value Other Financial Instruments Measured (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Mar. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market cash equivalents	$ 949	$ 288,446
Long-term British pound forward derivative contracts	4,359	7,042
Total fair value of assets	5,308	295,488
Quoted Prices In Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market cash equivalents	949	288,446
Total fair value of assets	949	288,446
Significant Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term British pound forward derivative contracts	4,359	7,042
Total fair value of assets	$ 4,359	$ 7,042