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]
Unrecognized tax benefits, beginning of year	$ 1,403	$ 1,222	$ 1,115
Increase related to prior year tax positions	0	133	104
Increase related to current year tax positions	116	128	160
Statute of limitations expiration	0	(80)	(157)
Unrecognized tax benefits, end of year	$ 1,519	$ 1,403	$ 1,222