COST OF REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Compensation and benefits	$ 30,463	$ 49,707	$ 108,637	$ 159,342
Outside fees and services	61,314	73,096	182,483	207,073
Cost of real estate sold	393	1,092	42,763	17,591
Technology and telecommunications	10,298	10,230	27,124	30,533
Reimbursable expenses	7,213	6,815	16,484	23,970
Depreciation and amortization	1,225	6,640	10,160	19,471
Cost of revenue	110,906	$ 147,580	$ 387,651	$ 457,980
Restatement Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Technology and telecommunications	1,600
Depreciation and amortization	$ (1,500)