RESTRUCTURING CHARGES - Schedule of Restructuring Activities (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Restructuring costs
Employee compensation costs	$ 0	$ 8,779,000
Fixed Asset disposals and accelerated depreciation of leasehold improvements	0	0
Other exit costs	0	238,000
Total restructuring costs	$ 0	$ 9,017,000