Debt (Long Term Debt Instruments) (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Mar. 31, 2012
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Debt instrument, weighted average interest rate	2.90%
Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Debt instrument, weighted average interest rate	2.80%
New 4.0% Notes [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	4.00%
Principal amount	$ 105,322	[1]	$ 105,322	[1]
New 4.25% Notes [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	4.25%
Principal amount	97,000	[1]	97,000	[1]
Original 4.0% Notes [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	4.00%
Principal amount	9,600	[2]	9,700	[2]
Original 4.25% Notes [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	4.25%
Principal amount	3,000	[2]	3,000	[2]
Unsecured Debt [Member] | 4.875% Senior Notes [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	4.875%
Principal amount	400,000
Unsecured Debt [Member] | 7.625% Senior Notes [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	7.625%
Principal amount	$ 150,000

[1] Dilutive shares associated with the New Convertible Notes are attributable to the premium over the respective conversion prices.

[2] Dilutive shares associated with the Original Convertible Notes are attributable to the underlying principal amounts.