Debt (Long Term Debt Instruments) (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012	Jun. 30, 2012
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Debt instrument, weighted average interest rate	2.70%
Loans Payable [Member]
Debt Instrument [Line Items]
Debt instrument, weighted average interest rate	3.10%
New 4.0% Notes [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	4.00%
Principal amount	$ 105,322	[1]	$ 105,300	$ 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	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 weighted average premium value, in shares, of the conversion shares underlying the New Convertible Notes in excess of the respective principal amounts thereof.

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