FAIR VALUE OF FINANCIAL INSTRUMENTS - Summary of Financial Assets and Liabilities Measured at Fair Value (Details) - Long-lived assets - Opop Tower and Lofts, St Louis, MO $ in Thousands	Jun. 30, 2021 USD ($)
Fair Value, Inputs, Level 1
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Non-Financial Assets:	$ 0
Fair Value, Inputs, Level 2
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Non-Financial Assets:	3,000
Fair Value, Inputs, Level 3
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Non-Financial Assets:	0
Estimate of Fair Value Measurement
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Non-Financial Assets:	$ 3,000