RESTRUCTURING CHARGES - Schedule of Restructuring Activities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restructuring costs
Employee compensation costs	$ 3,891	$ 16,852	$ 13,247
Fixed Asset disposals and accelerated depreciation of leasehold improvements	0	3,511	0
Other exit costs	0	238	0
Total restructuring costs	$ 3,891	$ 20,601	$ 13,247