Income Taxes - Income Tax Benefit Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of unrecognized tax benefits
Balance at January 1	$ 1,919	$ 1,606	$ 1,510
Additions based on positions related to current period	158	313	467
Reductions based on positions related to prior period	(1,410)	0	0
Reductions due to lapse of statute of limitations	0	0	(371)
Balance at December 31	$ 667	$ 1,919	$ 1,606