Summary of Significant Accounting Policies - Other Income (Expense) Net (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Foreign currency forward contract gain (loss), net	$ 10,085,000	$ (7,688,000)	$ (2,917,000)
Foreign currency transaction gain (loss), net	(2,824,000)	808,000	226,000
Other	518,000	9,000	1,001,000
Other income (expense), net	$ 7,779,000	$ (6,871,000)	$ (1,690,000)