Income Taxes - Schedule of Reconciliations of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Unrecognized tax benefits, opening balance	$ 1,931	$ 1,958	$ 464
Gross increases – tax positions in prior period			1,526
Gross increases – current period tax positions	20	35	29
Foreign currency translation	69	(43)	(37)
Lapse of statute of limitations	(93)	(19)	(24)
Unrecognized tax benefits, ending balance	$ 1,927	$ 1,931	$ 1,958