FAIR VALUE MEASUREMENT - Schedule of Financial Instruments Measured at Fair Value (Details) - Recurring basis - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Assets:
Purchase Options related to real estate loans	$ 7,161	$ 7,161
Level 1
Assets:
Purchase Options related to real estate loans	0	0
Level 2
Assets:
Purchase Options related to real estate loans	0	0
Level 3
Assets:
Purchase Options related to real estate loans	7,161	7,161
Interest rate swaps
Liabilities:
Derivative liabilities	23,285	30,850
Interest rate swaps | Level 1
Liabilities:
Derivative liabilities	0	0
Interest rate swaps | Level 2
Liabilities:
Derivative liabilities	23,285	30,850
Interest rate swaps | Level 3
Liabilities:
Derivative liabilities	$ 0	$ 0