COMMITMENTS, CONTINGENCIES AND REGULATORY MATTERS - Lease Activity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Lessee, Lease, Description [Line Items]
Cash used in operating activities for amounts included in the measurement of lease liabilities	$ 3,447	$ 3,720	$ 6,758	$ 8,457
Short-term (less than one year) lease costs	1,222	1,152	2,427	2,309
Selling, general and administrative expense
Lessee, Lease, Description [Line Items]
Operating lease costs	2,529	3,050	4,810	6,616
Cost of revenue
Lessee, Lease, Description [Line Items]
Operating lease costs	$ 635	$ 743	$ 1,269	$ 1,712