Segments - Reconciliation of Total Segment EBITDA to Income Before Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting [Abstract]
Total Segment EBITDA									$ 213,129	$ 496,225	$ 148,535
Depreciation and amortization									35,260	31,761	31,502
Other (expense) income									(6,175)	316,928	1,371
Income from operations	$ 52,742	$ 43,573	$ 48,811	$ 38,918	$ 42,277	$ 33,954	$ 38,250	$ 33,055	184,044	147,536	115,662
Interest expense, net									(46,065)	(35,283)	(27,125)
Other income (expense), net									(6,175)	316,928	1,371
Income before income taxes									$ 131,804	$ 429,181	$ 89,908