Income Taxes - Uncertain Tax Positions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Gross unrecognized tax benefits
Unrecognized tax benefits at the beginning of the period	$ 58,763	$ 52,404
Gross decrease in tax positions for prior years	(8,059)	(2,010)
Gross increase in tax positions for current year	12,743	8,369
Unrecognized tax benefits at the end of the period	$ 63,447	$ 58,763