Supplemental Financial Statement Information - Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts Notes And Loans Receivable Classified [Abstract]
Allowance for doubtful accounts, beginning of period	$ 13,976	$ 17,211	$ 19,392
Charged to costs and expenses	5,963	1,277	(5,986)
Account write-offs and other	(2,541)	(4,512)	3,805
Allowance for doubtful accounts, end of period	$ 17,398	$ 13,976	$ 17,211