SEGMENT INFORMATION - Schedule of Real Estate Investments, at Cost of Company's Reportable Segments (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Segment Reporting Information [Line Items]
Operating properties	$ 3,405,048	$ 3,374,780
Right of use asset - operating leases, net	18,259	18,412
Construction-in-progress	78,021	94,628
Land held for development	82,536	81,318
Prepaid leasehold interests in land held for development, net	27,762	27,762
Continuing Operations
Segment Reporting Information [Line Items]
Operating properties	3,405,048	3,374,780
Total Core Segments | Continuing Operations
Segment Reporting Information [Line Items]
Operating properties	3,122,588	3,097,025
Philadelphia CBD | Continuing Operations
Segment Reporting Information [Line Items]
Operating properties	1,578,547	1,556,696
Pennsylvania Suburbs | Continuing Operations
Segment Reporting Information [Line Items]
Operating properties	875,479	869,179
Austin, Texas | Continuing Operations
Segment Reporting Information [Line Items]
Operating properties	668,562	671,150
Other | Continuing Operations
Segment Reporting Information [Line Items]
Operating properties	$ 282,460	$ 277,755