Accounts Receivable, Net - Schedule of Changes in the Allowance for Doubtful Accounts on Accounts Receivable (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Receivables [Abstract]
Balance at beginning of period	$ (13,508)	$ (12,659)	$ (11,915)
Provision for losses	(5,529)	(4,154)	(5,804)
Charge-offs, net of recoveries	5,210	3,305	5,060
Balance at end of period	$ (13,827)	$ (13,508)	$ (12,659)