Income Taxes - Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance-beginning of year	$ 95,236	$ 90,523	$ 88,314
Increases based on tax positions of the current year	8,926	8,520	5,930
Reductions due to lapse in statutes of limitations	(4,692)	(3,807)	(3,721)
Balance-end of year	$ 99,470	$ 95,236	$ 90,523