Long-Term Debt - Schedule of Interest Expense, Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest Expense [Line Items]
Other interest	$ 18	$ 12	$ 10
Interest income	(991)	(247)	(110)
Total interest expense, net	81,617	81,419	86,504
Term Facility [Member]
Interest Expense [Line Items]
Interest expense	77,064	76,289	81,394
Amortization of deferred financing costs	4,044	3,925	3,810
Amortization of original issue discount	$ 1,482	$ 1,440	$ 1,400