Summary of Significant Accounting Policies - Other Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Foreign currency losses (gains)	$ 557	$ (253)	$ 853
Tax indemnification income	(2,855)	(8,367)	(1,055)
Other income	(167)	(18)	(18)
Total other income	$ (2,465)	$ (8,638)	$ (220)