REVENUE RECOGNITION Revenue Recognition - Contract Balances (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Accounts receivable, net of allowance for doubtful accounts of $758 and $647	$ 16,698		$ 16,698		$ 21,158
Deferred revenue	41,410		41,410		50,568
Deferred Revenue, Noncurrent	508		508		$ 1,058
Amounts included in the contract liability at the beginning of the period	$ 23,724	$ 27,122	$ 46,172	$ 49,653