SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS AND RESERVES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for doubtful accounts receivable and revenue adjustments
Changes in valuation and qualifying accounts and reserves
Balance at Beginning of Period	$ 5,448	$ 7,380	$ 7,657
Additions, Charged to Costs and Expenses	4,327	1,223	2,336
Additions, Charged to Other Accounts	1,887	(245)	863
Deductions	3,811	2,910	3,476
Balance at End of Period	7,851	5,448	7,380
Allowance for other accounts receivable
Changes in valuation and qualifying accounts and reserves
Balance at Beginning of Period	476	806	921
Additions, Charged to Costs and Expenses	(14)	(330)	(115)
Additions, Charged to Other Accounts	198
Balance at End of Period	660	476	806
Allowance for deferred tax assets
Changes in valuation and qualifying accounts and reserves
Balance at Beginning of Period	668	53	844
Deductions	(616)	(615)	791
Balance at End of Period	$ 1,284	$ 668	$ 53