REVENUE RECOGNITION Revenue Recognition - Contract Balances (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Accounts receivable, net of allowance for doubtful accounts of $758 and $647	$ 18,119		$ 18,119		$ 21,158
Deferred revenue	46,644		46,644		50,568
Deferred Revenue, Noncurrent	525		525		$ 1,058
Amounts included in the contract liability at the beginning of the period	$ 25,303	$ 26,613	$ 37,550	$ 39,961