SEGMENT INFORMATION - Schedule of Unconsolidated Real Estate Ventures of Company's Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Investment in real estate ventures	$ 594,203		$ 594,203		$ 570,455
Equity in income (loss) of real estate ventures	(18,183)	$ (125,862)	(43,526)	$ (153,957)
Philadelphia CBD
Segment Reporting Information [Line Items]
Investment in real estate ventures	492,224		492,224		452,334
Equity in income (loss) of real estate ventures	(10,325)	(125,593)	(22,184)	(145,429)
Mid-Atlantic Office JV
Segment Reporting Information [Line Items]
Investment in real estate ventures	10,951		10,951		10,844
Equity in income (loss) of real estate ventures	(168)	7,222	107	7,222
MAP Venture
Segment Reporting Information [Line Items]
Investment in real estate ventures	0		0		0
Equity in income (loss) of real estate ventures	0	10	0	(6,552)
Austin, Texas
Segment Reporting Information [Line Items]
Investment in real estate ventures	74,101		74,101		90,495
Equity in income (loss) of real estate ventures	(7,510)	(586)	(20,908)	(590)
Other
Segment Reporting Information [Line Items]
Investment in real estate ventures	16,927		16,927		$ 16,782
Equity in income (loss) of real estate ventures	$ (180)	$ (6,915)	$ (541)	$ (8,608)