Components of Long-Term Debt (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Jun. 13, 2012	Dec. 31, 2011
Line of Credit Facility [Line Items]
Long-term debt, Gross	$ 1,025,000		$ 1,025,000
Less: Unamortized debt discount on 3.875% Convertible Senior Subordinated Notes due 2017	(59,720)		(70,191)
Total long-term debt	965,280		954,809
Term loan facility, at a rate of 2.75%, due 10/1/2014
Line of Credit Facility [Line Items]
Term loan facility, at a rate of 2.75%, due 10/1/2014	375,000		375,000
3.875% Convertible Senior Subordinated Notes Due 2017
Line of Credit Facility [Line Items]
3.875% Convertible Senior Subordinated Notes due 2017	400,000		400,000
6.875% Senior Subordinated Notes Due 2019
Line of Credit Facility [Line Items]
6.875% Senior Subordinated Notes due 2019	$ 250,000	$ 250,000	$ 250,000