Income Taxes - Schedule of Changes in Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Unrecognized tax benefits, beginning balance	$ 142,845	$ 140,889	$ 133,491
Additions based on tax positions related to current	9,043	8,876	7,738
Additions for tax positions of prior years	68	82	171
Reductions for tax positions of prior years	(856)	(2,817)	(511)
Decreases related to settlements of prior year tax positions		(4,185)
Unrecognized tax benefits, ending balance	$ 151,100	$ 142,845	$ 140,889