ACCOUNTS RECEIVABLE AND RELATED ALLOWANCE FOR DOUBTFUL ACCOUNTS AND SALES RESERVES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts Receivable
Accounts receivable	$ 396,427	$ 359,456
Allowance for doubtful accounts and sales reserves	(17,515)	(16,690)
Accounts receivable, net of allowance for doubtful accounts and sales reserves	378,912	342,766
Allowance for Doubtful Accounts
Balance At Beginning Of Year	9,419	3,885	$ 2,137
Additions Charged To Costs And Expenses	4,549	8,909	3,715
Deductions From Reserves	(5,703)	(3,375)	(1,967)
Balance At End Of Year	8,265	9,419	3,885
Allowance for Sales Reserves
Allowance for Sales Reserve	7,271	390	0
Additions Charged To Revenues	11,394	14,254	390
Deductions From Reserves	(9,415)	(7,373)	0
Allowance for Sales Reserve	$ 9,250	$ 7,271	$ 390