Income Taxes - Reconciliation of Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ 9,450	$ 15,054	$ 30,410
Increases in tax positions for current year	73	211	251
Increases in tax positions for prior years	5,159	244	904
Decreases in tax positions for prior years	(6,674)	(5,842)	(53)
Settlement of tax matters	0	(217)	0
Lapse of applicable statutes of limitations	(3,227)	0	(16,458)
Balance at end of year	$ 4,781	$ 9,450	$ 15,054