DEFERRED CONTRACT COSTS - Schedule of Amortization of Deferred Contract Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Amortization of deferred contract costs	$ 5,878	$ 3,809	$ 14,179	$ 7,598