PROPERTY AND EQUIPMENT, NET - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 327,723	$ 267,311
Less: Accumulated depreciation and amortization	(178,529)	(124,909)
Property and equipment, net	149,194	142,402
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	111,942	107,611
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	106,469	80,093
Capitalized software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	81,984	58,908
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 27,328	$ 20,699