Debt and Credit Agreements - Changes in the Balance of Deferred Debt Issuance Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Change In Debt Issuance Costs, Net [Roll Forward]
Balance	$ 4,700
Additions	550	$ 2,321	$ 0
Amortization	(1,597)	(2,204)	(2,292)
Balance	4,253	4,700
Line of Credit
Change In Debt Issuance Costs, Net [Roll Forward]
Balance	4,700
Additions	550
Amortization	(997)	(2,200)	$ (2,300)
Balance	$ 4,253	$ 4,700