Valuation Allowance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Beginning valuation allowance	$ 131,389	$ 109,274
Increase as reflected in income tax expense	13,609	11,466
Cumulative translation adjustment	(4,881)	10,649
Ending valuation allowance	$ 140,117	$ 131,389