COST OF REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cost of Revenue [Abstract]
Compensation and benefits	$ 54,866	$ 63,092
Outside fees and services	65,098	80,959
Cost of real estate sold	3,179	4,935
Technology and telecommunications	9,451	11,351
Reimbursable expenses	8,147	10,029
Depreciation and amortization	6,453	7,587
Cost of revenue	$ 147,194	$ 177,953