Long-Term Debt - Credit Facility Net Interest Expense (Details) - Revolving Credit Facility - Line of Credit - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest Expense and Amortization of Debt Issue Costs
Interest expense	$ 6,618	$ 1,865	$ 0
Debt issue cost amortization	1,012	565	47
Unused facility fee	354	627	71
Total	$ 7,984	$ 3,057	$ 118