COMMITMENTS, CONTINGENCIES AND REGULATORY MATTERS - Lease Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Cash used in operating activities for amounts included in the measurement of lease liabilities	$ 13,113	$ 15,446
Short-term (twelve months or less) lease costs	3,797	4,999
Selling, general and administrative expense
Lessee, Lease, Description [Line Items]
Operating lease costs	9,712	10,698
Cost of revenue
Lessee, Lease, Description [Line Items]
Operating lease costs	$ 1,919	$ 2,757