Business Description and Summary of Significant Accounting Policies - Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Business Description and Summary of Significant Accounting Policies
Income tax expense	$ 148	$ 504
Income tax expense (% Change)		(70.60%)
Effective tax rate	21.50%	21.00%
Effective tax rate (% Change)		2.40%