Income Taxes - Additional Information (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 [Line Items]
Tax benefit related to 2017 Tax Act										$ (44,900)
Valuation allowance	$ 21,929				$ 21,621				$ 21,929	21,621
Foreign withholding tax	(413)				(1,035)				(413)	(1,035)
Deferred tax liability not recognized related to tax basis difference in investment in foreign subsidiaries	17,800								17,800
Income tax provision	7,834	$ 19,964	$ 14,113	$ 15,270	(38,458)	$ 9,197	$ 527	$ 7,877	57,181	(20,857)	$ 42,283
Liability for uncertain tax positions	$ 3,700				$ 2,700				$ 3,700	$ 2,700