NOTES AND BONDS PAYABLE - Schedule of Long-term Debt Instruments (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Total Notes and Bonds Payable principal outstanding	$ 763,070	$ 678,080
Premium on Notes and Bonds Payable	175	783
Deferred financing costs, net	(5,170)	(5,200)
Notes and Bond Payable, Net	758,075	673,663
Mortgages \| Richardson Portfolio Mortgage Loan
Debt Instrument [Line Items]
Notes payable, net	$ 36,000	36,000
Interest rate, effective percentage	2.65%
Mortgages \| Richardson Portfolio Mortgage Loan \| One-month LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	2.50%
Mortgages \| Park Centre Mortgage Loan
Debt Instrument [Line Items]
Notes payable, net	$ 21,970	21,970
Interest rate, effective percentage	1.90%
Mortgages \| Park Centre Mortgage Loan \| One-month LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.75%
Mortgages \| 1180 Raymond Mortgage Loan
Debt Instrument [Line Items]
Notes payable, net	$ 29,948	30,250
Interest rate, effective percentage	3.50%
Mortgages \| 1180 Raymond Mortgage Loan \| One-month LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	2.50%
Mortgages \| 1180 Raymond Bond Payable
Debt Instrument [Line Items]
Bonds payable	$ 5,930	6,080
Contractual interest rate, percentage	6.50%
Interest rate, effective percentage	6.50%
Mortgages \| Pacific Oak SOR (BVI) Holdings, Ltd. Series A Debentures
Debt Instrument [Line Items]
Notes payable, net	$ 169,927	224,746
Contractual interest rate, percentage	4.25%
Interest rate, effective percentage	4.25%
Mortgages \| Pacific Oak SOR (BVI) Holdings, Ltd. Series B Debentures
Debt Instrument [Line Items]
Notes payable, net	$ 74,159	0
Contractual interest rate, percentage	3.93%
Interest rate, effective percentage	3.93%
Mortgages \| Crown Pointe Mortgage Loan
Debt Instrument [Line Items]
Notes payable, net	$ 53,254	51,171
Interest rate, effective percentage	2.75%
Mortgages \| Crown Pointe Mortgage Loan \| One-month LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	2.60%
Mortgages \| City Tower Mortgage Loan
Debt Instrument [Line Items]
Notes payable, net	$ 94,167	89,000
Interest rate, effective percentage	1.70%
Mortgages \| City Tower Mortgage Loan \| One-month LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.55%
Mortgages \| The Marq Mortgage Loan
Debt Instrument [Line Items]
Notes payable, net	$ 58,331	53,408
Interest rate, effective percentage	1.70%
Mortgages \| The Marq Mortgage Loan \| One-month LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.55%
Mortgages \| Eight & Nine Corporate Centre Mortgage Loan
Debt Instrument [Line Items]
Notes payable, net	$ 47,066	43,880
Interest rate, effective percentage	1.75%
Mortgages \| Eight & Nine Corporate Centre Mortgage Loan \| One-month LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.60%
Mortgages \| Georgia 400 Center Mortgage Loan
Debt Instrument [Line Items]
Notes payable, net	$ 59,690	59,690
Interest rate, effective percentage	1.70%
Mortgages \| Georgia 400 Center Mortgage Loan \| One-month LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.55%
Mortgages \| PORT Mortgage Loan 1
Debt Instrument [Line Items]
Notes payable, net	$ 51,362	51,362
Contractual interest rate, percentage	4.74%
Interest rate, effective percentage	4.74%
Mortgages \| PORT Mortgage Loan 2
Debt Instrument [Line Items]
Notes payable, net	$ 10,523	10,523
Contractual interest rate, percentage	4.72%
Interest rate, effective percentage	4.72%
Mortgages \| PORT Mortgage Loan 3
Debt Instrument [Line Items]
Notes payable, net	$ 12,000	0
Contractual interest rate, percentage	5.00%
Interest rate, effective percentage	5.00%
Mortgages \| PORT Mortgage Loan 3 \| From December 1, 2020 through March 31, 2021
Debt Instrument [Line Items]
Contractual interest rate, percentage	6.50%
Mortgages \| Battery Point Trust Mortgage Loan
Debt Instrument [Line Items]
Notes payable, net	$ 38,743	$ 0
Contractual interest rate, percentage	2.50%
Interest rate, effective percentage	3.50%
Mortgages \| Battery Point Trust Mortgage Loan \| One-month LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%

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Notes and Bond Payable, Net

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Amount, after accumulated amortization, of debt premium.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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