Income Taxes - Components of Income Before Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
United States									$ 16,312	$ (42,863)	$ 134,740
Foreign									75,487	86,435	50,841
Income before income taxes	$ 108,744	$ 17,245	$ (10,810)	$ (23,380)	$ 98,922	$ 1,155	$ (50,723)	$ (5,782)	$ 91,799	$ 43,572	$ 185,581