Income Taxes - Rollforward of Total Gross Unrecognized Tax Benefit (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefit as of beginning of period	$ 33,262	$ 47,656	$ 46,384
Tax positions related to current year, additions for uncertain tax positions	19,012	14,519	1,819
Tax positions related to prior year, Additions for uncertain tax positions	143	80	1,809
Tax positions related to prior year, Decreases for uncertain tax positions	(3,783)		(826)
Tax positions related to prior year, Settlements with tax authorities			(1,527)
Tax positions related to prior year, Reductions due to lapse of applicable statute of limitations	(1,984)	(28,993)	(3)
Unrecognized tax benefit as of end of period	$ 46,650	$ 33,262	$ 47,656