Segments - Reconciliation of Total Segment EBITDA to Income Before Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting [Abstract]
Total Segment EBITDA	$ 74,399	$ 56,928	$ 134,173	$ 104,503
Depreciation and amortization	10,577	8,619	20,484	17,084
Other expense	(1,444)	(502)	(4,762)	(310)
Income from operations	65,266	48,811	118,451	87,729
Interest income	1,979	418	3,777	455
Interest expense	(14,636)	(9,046)	(29,385)	(17,816)
Income before income taxes	$ 51,165	$ 39,681	$ 88,081	$ 70,058