Income Taxes - Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at January 1	$ 137,929	$ 119,818	$ 116,070
Increases for positions taken in current year	5,969	3,836	7,548
Increases for positions taken in a prior year	5,811	29,487	25,239
Decreases for positions taken in a prior year	(3,127)	(10,150)	(1,813)
Decreases for settlements with taxing authorities	(3,410)	(1,982)	(1,143)
Decreases for lapses in the applicable statute of limitations	(2,863)	(3,080)	(26,083)
Unrecognized tax benefits at December 31	$ 140,309	$ 137,929	$ 119,818