COST OF REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Cost of Revenue [Abstract]
Compensation and benefits	$ 49,707	$ 60,332	$ 159,342	$ 186,090
Outside fees and services	73,096	83,670	207,073	250,883
Cost of real estate sold	1,092	4,411	17,591	16,461
Technology and telecommunications	10,230	10,389	30,533	32,681
Reimbursable expenses	6,815	9,866	23,970	31,786
Depreciation and amortization	6,640	6,230	19,471	20,343
Cost of revenue	$ 147,580	$ 174,898	$ 457,980	$ 538,244