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, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Segment Reporting Information [Line Items]
Investment in real estate ventures	$ 602,700		$ 602,700		$ 552,494
Equity in income (loss) of real estate ventures	(125,862)	$ (10,739)	(153,957)	$ (24,504)
Philadelphia CBD
Segment Reporting Information [Line Items]
Investment in real estate ventures	419,700		419,700		450,136
Equity in income (loss) of real estate ventures	(125,593)	(6,537)	(145,429)	(14,208)
Metropolitan Washington, D.C.
Segment Reporting Information [Line Items]
Investment in real estate ventures	86,666		86,666		71,931
Equity in income (loss) of real estate ventures	(6,915)	(1,306)	(8,608)	(3,896)
Mid-Atlantic Office JV
Segment Reporting Information [Line Items]
Investment in real estate ventures	10,925		10,925		0
Equity in income (loss) of real estate ventures	7,222	182	7,222	595
MAP Venture
Segment Reporting Information [Line Items]
Investment in real estate ventures	0		0		(48,733)
Equity in income (loss) of real estate ventures	10	(3,078)	(6,552)	(6,995)
Austin, Texas
Segment Reporting Information [Line Items]
Investment in real estate ventures	85,409		85,409		$ 79,160
Equity in income (loss) of real estate ventures	$ (586)	$ 0	$ (590)	$ 0