Income Taxes - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Balance of unrecognized tax benefits at beginning of year	$ 27,237	$ 24,278	$ 21,079
Increases for tax positions of prior years	315	2,478	58
Decreases for tax positions of prior years	(61)	(114)	(361)
Increases for tax positions established for the current period	1,185	1,677	5,185
Decreases for settlements with taxing authorities		(154)	(167)
Reductions resulting from lapse of applicable statute of limitation	(115)	(1,155)	(1,310)
Adjustment resulting from foreign currency translation	(155)	227	(206)
Balance of unrecognized tax benefits at end of year	$ 28,406	$ 27,237	$ 24,278