Income Taxes - Unrecognized Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Unrecognized tax expense rollforward
Increase related to prior year tax positions	$ 91
Increase related to current year tax positions	13
Unrecognized tax expense, end of year	104
Interest and penalties on unrecognized tax benefit	$ 156	$ 0