Schedule II - Valuation and Qualifying Accounts (Details) - Allowance for doubtful accounts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 3,195	$ 4,183	$ 4,574
Charged to Cost and Expenses	621	190	823
Charged to Other Accounts	76
Deductions, Actual Charge-Offs	(1,218)	(1,178)	(1,214)
Balance at End of Period	$ 2,674	$ 3,195	$ 4,183