Income Taxes - Income Tax Benefit Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of unrecognized tax benefits
Balance at January 1	$ 667	$ 1,919	$ 1,606
Additions based on positions related to current period	101	158	313
Reductions based on positions related to prior period	(314)	(1,410)	0
Reductions due to lapse of statute of limitations	(52)	0	0
Balance at December 31	$ 402	$ 667	$ 1,919