LEASES - Undiscounted Cash Flows (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Leases [Abstract]
2019	$ 1,254
2020	6,775
2021	5,924
2022	5,042
2023	4,696
Thereafter	5,869
Total minimum lease payments	29,560
Less: amount of lease payments representing interest	(4,512)
Present value of future minimum lease payments	25,048	$ 28,600
Less: current lease obligations	(4,936)		$ 0
Non-current lease obligations	$ 20,112		$ 0