FAIR VALUE MEASUREMENT - Schedule of Unobservable Inputs for Fair Values of Purchase Options (Details) - Recurring basis - Level 3 $ / shares in Thousands	6 Months Ended
	Jun. 30, 2020 $ / shares
Real Estate Loan 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, term	2 years 7 months 2 days
Real Estate Loan 1 | Exercise price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, measurement input	15,143
Real Estate Loan 1 | Expected volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, measurement input	0.650
Real Estate Loan 1 | Risk-free rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, measurement input	0.003
Real Estate Loan 1 | Expected annualized equity dividend yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, measurement input	0.065
Real Estate Loan 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, term	2 years 8 months 4 days
Real Estate Loan 2 | Exercise price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, measurement input	17,377
Real Estate Loan 2 | Expected volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, measurement input	0.550
Real Estate Loan 2 | Risk-free rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, measurement input	0.003
Real Estate Loan 2 | Expected annualized equity dividend yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, measurement input	0.075
Real Estate Loan 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, term	2 years 8 months 1 day
Real Estate Loan 3 | Exercise price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, measurement input	5,503
Real Estate Loan 3 | Expected volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, measurement input	0.550
Real Estate Loan 3 | Risk-free rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, measurement input	0.003
Real Estate Loan 3 | Expected annualized equity dividend yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, measurement input	0.171
Real Estate Loan 4
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, term	1 year 5 months 1 day
Real Estate Loan 4 | Exercise price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, measurement input	37,800
Real Estate Loan 4 | Expected volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, measurement input	0.550
Real Estate Loan 4 | Risk-free rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, measurement input	0.002
Real Estate Loan 4 | Expected annualized equity dividend yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase options, measurement input	0