Income Taxes - Reconciliation 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, Beginning Balance	$ 1,774	$ 1,910	$ 2,136
Additions for tax positions of prior years			36
Reductions for tax positions of prior years		(31)
Additions for tax positions of current year		75	46
Settlements	(986)	(163)	(303)
Translation adjustments	18	(17)	(5)
Unrecognized tax benefits, Ending Balance	$ 806	$ 1,774	$ 1,910