Income Taxes - Reconciliation of Amount of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Beginning Balance	$ 4,061	$ 332	$ 287
Decreases based on tax positions taken during a prior period	(3,559)		(102)
Increases based on tax positions taken during a prior period	4,628	3,562
Increases based on tax positions taken during a current period	4,986	167	147
Ending Balance	$ 10,116	$ 4,061	$ 332