FAIR VALUE MEASUREMENT - Narrative (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018 USD ($) hotel	Jun. 30, 2018 USD ($) Loan hotel
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of hotels | hotel	80	80
Mezzanine Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of construction loans | Loan		3
Net amount of loan receivable	$ 29.6	$ 29.6
Number of hotels | hotel	3	3
Interest rate		8.00%
Loans initial term		3 years
Funded amount of loan receivable	$ 29.6	$ 29.6
Interest in hotel upon completion to purchase	90.00%	90.00%
Period of time after initial option exercise to purchase remaining interests		5 years
Amortization of discount	$ 0.5	$ 1.0
Other Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options related to real estate loans	$ 6.1	$ 6.1