Long-term Debt - Debt Issuance Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Debt issuance costs	$ (4,160)	$ (5,310)
Amortization of Debt Issuance Costs	$ 1,150	$ 1,130	$ 1,290