Segments - Reconciliation of Total Segment EBITDA to Income Before Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting [Abstract]
Total Segment EBITDA	$ 64,832	$ 52,409	$ 199,005	$ 156,911
Depreciation and amortization	11,832	8,863	32,316	25,947
Other expense	(61)	(27)	(4,824)	(338)
Income from operations	53,061	43,573	171,513	131,302
Interest income	1,808	2,025	5,585	2,480
Interest expense	(14,807)	(17,909)	(44,192)	(35,725)
Income before income taxes	$ 40,001	$ 27,662	$ 128,082	$ 97,719