SEGMENT INFORMATION - Schedule of Unconsolidated Real Estate Ventures of Company's Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Investment in real estate ventures	$ 555,541		$ 555,541		$ 570,455
Equity in income (loss) of real estate ventures	(14,832)	$ (14,507)	(25,343)	$ (28,095)
Philadelphia CBD
Segment Reporting Information [Line Items]
Investment in real estate ventures	453,070		453,070		452,334
Equity in income (loss) of real estate ventures	(7,651)	(10,223)	(11,859)	(19,836)
Mid-Atlantic Office JV
Segment Reporting Information [Line Items]
Investment in real estate ventures	11,119		11,119		10,844
Equity in income (loss) of real estate ventures	436	0	275	(1,693)
MAP Venture
Segment Reporting Information [Line Items]
Investment in real estate ventures	0		0		0
Equity in income (loss) of real estate ventures	0	(3,339)	0	(6,562)
Austin, Texas
Segment Reporting Information [Line Items]
Investment in real estate ventures	74,605		74,605		90,495
Equity in income (loss) of real estate ventures	(7,510)	(4)	(13,398)	(4)
Other
Segment Reporting Information [Line Items]
Investment in real estate ventures	16,747		16,747		$ 16,782
Equity in income (loss) of real estate ventures	$ (107)	$ (941)	$ (361)	$ 0