COMMITMENTS AND CONTINGENCIES - Lease Cost (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2021 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Right-of-use asset (included in real estate held for investment, net)	$ 8,074	$ 8,074
Lease obligation (included in other liabilities)	$ 9,339	$ 9,339
Remaining lease term	92 years 6 months	92 years 6 months
Discount rate	4.80%	4.80%
Interest on lease obligation for the nine months ended September 30, 2021		$ 441
210 West 31st
Real Estate Properties [Line Items]
Right-of-use asset impairment	$ 1,200	$ 1,200