Selected Quarterly Financial Data (Unaudited) - Schedule of Selected Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Revenues, net	$ 430,601	$ 451,493	$ 404,605	$ 416,166	$ 376,697	$ 295,283	$ 273,502	$ 253,908	$ 1,702,865	$ 1,199,390	$ 895,171
Operating income	146,149	188,460	169,151	163,774	172,622	144,207	134,484	114,136	667,534	565,449	420,632
Net income	$ 52,830	$ 116,770	$ 98,678	$ 94,153	$ 109,540	$ 95,509	$ 88,549	$ 75,109	$ 362,431	$ 368,707	$ 284,501
Earnings per share:
Basic earnings per share	$ 0.57	$ 1.27	$ 1.07	$ 1.03	$ 1.25	$ 1.14	$ 1.07	$ 0.91	$ 3.94	$ 4.37	$ 3.48
Diluted earnings per share	$ 0.56	$ 1.24	$ 1.05	$ 1.00	$ 1.21	$ 1.11	$ 1.03	$ 0.88	$ 3.85	$ 4.24	$ 3.36
Weighted average shares outstanding:
Basic weighted average shares outstanding	92,321	92,110	91,904	91,750	87,877	83,611	82,996	82,737	92,023	84,317	81,793
Diluted weighted average shares outstanding	94,350	94,157	94,050	93,934	90,240	86,134	85,817	85,695	94,139	86,982	84,655