Long-term Debt - Long-Term Debt (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Debt	$ 2,423,990	$ 1,919,484
Debt, Less current maturities	(28,713)	(21,332)
Debt, excluding current maturities	2,395,277	1,898,152
Deferred financing costs	31,313	28,034
Deferred financing costs, Less current maturities	(5,344)	(4,823)
Deferred financing costs, excluding current maturities	25,969	23,211
Debt, net of deferred financing costs	2,392,677	1,891,450
Debt, net of deferred financing costs, Less current maturities	(23,369)	(16,509)
Debt, net of deferred financing costs, excluding current maturities	2,369,308	1,874,941
Senior Credit Facility [Member]
Debt Instrument [Line Items]
Debt	478,375	373,750
Deferred financing costs	5,913	7,058
Debt, net of deferred financing costs	472,462	366,692
5 7/8% Senior Subordinated Notes [Member]
Debt Instrument [Line Items]
Debt	500,000	500,000
Deferred financing costs	7,654	8,219
Debt, net of deferred financing costs	492,346	491,781
5% Senior Subordinated Notes [Member]
Debt Instrument [Line Items]
Debt	535,000	535,000
Deferred financing costs	6,084	6,451
Debt, net of deferred financing costs	528,916	528,549
5 3/8% Senior Notes [Member]
Debt Instrument [Line Items]
Debt	510,000	510,000
Deferred financing costs	5,988	6,306
Debt, net of deferred financing costs	504,012	503,694
5 3/4% Senior Notes [Member]
Debt Instrument [Line Items]
Debt	400,000
Deferred financing costs	5,674
Debt, net of deferred financing costs	394,326
Other Notes with Various Rates and Terms [Member]
Debt Instrument [Line Items]
Debt	615	734
Debt, net of deferred financing costs	$ 615	$ 734