FAIR VALUE MEASUREMENTS - Financial Assets and Liabilities Not Measured at Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
FINANCIAL LIABILITIES
Mortgages payable	$ 595,230
Carrying Amount
FINANCIAL ASSETS
Cash and cash equivalents	52,714	$ 26,579
Mortgage and note receivable	0	32,810
FINANCIAL LIABILITIES
Revolving lines of credit	63,000	50,079
Notes payable	270,000	270,000
Mortgages payable	325,230	331,376
Carrying Amount | Restricted cash
FINANCIAL ASSETS
Cash and cash equivalents	2,535	19,538
Fair Value
FINANCIAL ASSETS
Cash and cash equivalents	52,714	26,579
Mortgage and note receivable	0	32,810
FINANCIAL LIABILITIES
Revolving lines of credit	63,000	50,079
Notes payable	270,000	270,000
Mortgages payable	334,234	332,471
Fair Value | Restricted cash
FINANCIAL ASSETS
Cash and cash equivalents	$ 2,535	$ 19,538