SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and equipment	$ 450,045	$ 379,139
Less accumulated depreciation	(217,092)	(188,265)
Net property and equipment	232,953	190,874
Furniture, fixtures, and equipment
Property, Plant and Equipment [Line Items]
Property and equipment	$ 236,180	200,215
Furniture, fixtures, and equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful Lives (in years)	3 years
Furniture, fixtures, and equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful Lives (in years)	12 years
Buildings
Property, Plant and Equipment [Line Items]
Property and equipment	$ 130,050	110,056
Buildings | Minimum
Property, Plant and Equipment [Line Items]
Useful Lives (in years)	3 years
Buildings | Maximum
Property, Plant and Equipment [Line Items]
Useful Lives (in years)	30 years
Corporate aircraft
Property, Plant and Equipment [Line Items]
Useful Lives (in years)	10 years
Property and equipment	$ 11,334	11,334
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	$ 40,312	28,178
Leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Useful Lives (in years)	3 years
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Useful Lives (in years)	15 years
Land
Property, Plant and Equipment [Line Items]
Property and equipment	$ 23,635	23,759
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment	$ 8,534	$ 5,597