PROPERTY AND EQUIPMENT - Components of Property and Equipment, net (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 105,258	$ 98,232
Less: accumulated depreciation	(70,975)	(61,597)
Property and equipment, net	34,283	36,635
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	42,162	39,216
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	25,147	25,285
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	8,524	8,517
Computer software purchased
Property, Plant and Equipment [Line Items]
Property and equipment, gross	7,775	7,578
Computer software developed for internal use
Property, Plant and Equipment [Line Items]
Property and equipment, gross	17,606	16,463
Fixed assets in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 4,044	$ 1,173

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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