Income Taxes - Unrecognized Tax Benefits (Details) - 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]
Balance at beginning of year	$ 27,359	$ 64,892	$ 85,845
Gross increases – tax positions of prior periods	2,539	74	2,704
Gross increases – current period tax positions	1,946	2,006	3,021
Gross decreases – tax positions of prior periods	(3,540)	(5,201)	(15,287)
Gross decreases – lapse of applicable statute of limitations	(4,199)	(28,672)	(6,186)
Gross decreases – settlements	0	(5,740)	(5,205)
Balance at end of year	$ 24,105	$ 27,359	$ 64,892