Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Gross
Receivables	$ 26,932		$ 26,932		$ 18,512
Long-term contract receivable	33,094		33,094		34,818
Total	60,026		60,026		53,330
CECL Allowance
Receivables	(2,581)		(2,581)		(2,358)
Long-term contract receivable	(1,146)		(1,146)		(1,554)
Total	(3,727)		(3,727)		(3,912)
Net
Receivables	24,351		24,351		16,154
Long-term contract receivable	31,948		31,948		33,264
Total	56,299		56,299		$ 49,418
Credit Loss, Expense (Reversal)	$ 500	$ 300	$ (200)	$ 0