REVENUE AND CONTRACT LIABILITY Sales Return Allowance (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Sales returns allowance [Abstract]
Sales Return, Reserve for Sales Returns, Current	$ 17,916	$ 11,107	$ 15,261
Sales Returns, Additions To Reserve For Sales Returns	143,746	117,040
Deductions From Sales Returns, Current	$ (136,937)	$ (121,194)