Allowance for Doubtful Accounts - Summary of Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for Doubtful Accounts Receivable [Roll Forward]
Beginning balance	$ 2,534	$ 2,575	$ 5,376
Provision charged to income	3,790	963	1,407
Write-offs	(2,708)	(1,134)	(4,106)
Foreign currency translation	114	(130)	102
Ending balance	$ 3,502	$ 2,534	$ 2,575