REVENUE RECOGNITION - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Deferred revenue			$ 64,100
Deferred revenue recognized during period	$ 41,000	$ 54,100
Deferred revenue	69,411	69,411		$ 62,371
Noncurrent deferred revenue	1,000	1,000
Amortization expense recognized related to contract cost assets		12,500
Capitalization of costs incurred to obtain contract	$ 42,100	$ 42,100