Income Taxes - Summary of Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current provision:
Domestic	$ 17,407	$ 7,107	$ 9,951
Foreign	18,008	18,428	12,022
Total	35,415	25,535	21,973
Deferred provision/(benefit):
Domestic	2,618	(2,506)	3,041
Foreign	(1,887)	(878)	(803)
Total	731	(3,384)	2,238
Income tax expense	$ 36,146	$ 22,151	$ 24,211