COST OF REVENUE (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cost of Revenue [Abstract]
Compensation and benefits	$ 94,365	$ 135,502	$ 200,486
Outside fees and services	146,322	240,796	278,380
Technology and telecommunications	35,912	36,302	41,588
Reimbursable expenses	16,285	24,172	30,039
Depreciation and amortization	12,310	13,721	24,013
Cost of real estate sold	0	42,763	47,659
Total	$ 305,194	$ 493,256	$ 622,165