REAL ESTATE INVESTMENTS - Schedule of Property Dispositions (Details) $ in Thousands							3 Months Ended		9 Months Ended
	Sep. 30, 2022 USD ($)	Jul. 29, 2022 USD ($) a	Jul. 14, 2022 USD ($) a	Jun. 28, 2022 USD ($)	Apr. 14, 2022 USD ($) a	Jan. 20, 2022 USD ($) a	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Jun. 28, 2022 a	Jun. 28, 2022 ft²
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain on disposition of real estate							$ 8,669	$ 0	$ 8,813	$ 142
Land | Gateway G & H
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rentable Square Feet/Acres | a						10.0
Sales Price						$ 1,600
Net gain on disposition of real estate						$ 897
Land | 25 M Street
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rentable Square Feet/Acres | a					0.8
Sales Price					$ 29,675
Net gain on disposition of real estate	$ 400				$ 3,836
Land | Gibbsboro Portfolio
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain on disposition of real estate									700
Land | 11501 Burnet Road
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rentable Square Feet/Acres | a		4.7
Sales Price		$ 32,513
Net gain on disposition of real estate		$ 8,312
Office/Land | Gibbsboro Portfolio
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rentable Square Feet/Acres											4.0	42,809
Sales Price				$ 4,100
Net gain on disposition of real estate				$ 831
Leasehold Interest | 3151 Market Street
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rentable Square Feet/Acres | a			0.8
Sales Price			$ 30,394
Net gain on disposition of real estate			$ 2,583
Office properties | Gibbsboro Portfolio
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain on disposition of real estate									$ 100