Income Taxes - Summary of Reconciliation of Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Gross Unrecognized Tax Benefits
Beginning balance	$ 19,892	$ 18,647	$ 30,713
Additions based on tax positions related to prior years	3,958	1,245	1,408
Settlements with taxing authorities	(4,820)	0	(9,050)
Reductions due to expiration of statute of limitations	(2,886)	0	(4,424)
Ending balance	$ 16,144	$ 19,892	$ 18,647