Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for uncollectible receivables
Balance at beginning of period	$ 2,279	$ 3,764	$ 11,453
Charge to expenses	5,051	2,859	(2,275)
Additions/(deductions)	(1,891)	(4,344)	(5,414)
Balance at end of period	5,439	2,279	3,764
Valuation allowance for deferred tax assets
Balance at beginning of period	24,747	8,361	713
Charge to expenses	1,877	16,386	7,648
Additions/(deductions)	0	0	0
Balance at end of period	$ 26,624	$ 24,747	$ 8,361