Debt - Summary of Outstanding Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Total debt	$ 1,829,750	$ 1,957,000
Less: current portion	19,075	13,500
Total long-term debt	1,810,675	1,943,500
Bank Credit Facility [Member]
Debt Instrument [Line Items]
Total debt	1,329,750	1,457,000
5 1/2% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Total debt	200,000	200,000
6 3/8% Senior Notes Due 2023 [Member]
Debt Instrument [Line Items]
Total debt	$ 300,000	$ 300,000