Components of Net Carrying Amount of Convertible Notes (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Mar. 31, 2012
Debt Instrument [Line Items]
Net carrying amount	$ 155,273	$ 239,129
Convertible Notes Payable
Debt Instrument [Line Items]
Principal	172,500	172,500
Unamortized discount	(17,227)	(24,228)
Net carrying amount	155,273	148,272
Carrying amount of equity component	$ 29,850	$ 29,850

Including current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date before deducting unamortized discount or premiums (if any). May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer.

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The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

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- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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