Schedule II Valuation and Qualifying Accounts and Reserves Supplemental Schedule (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2018
Accounts receivable reserves
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 2,078	$ 2,800	$ 1,858
Charged to Costs and Expenses	2,441	1,255	1,874
Charged to Other Accounts	0	0	0
Deductions	(1,315)	(1,977)	(932)
Balance at End of Period	3,204	2,800	2,800
Accounts receivable reserves | Difference between Revenue Guidance in Effect before and after Topic 606
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period		475
Deferred tax assets valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	114	1,747	1,733
Charged to Costs and Expenses	0	0	14
Charged to Other Accounts	0	0	0
Deductions	(114)	(1,633)	0
Balance at End of Period	$ 0	$ 1,747	$ 1,747