Debt (Narrative) (Details) ft² in Thousands, $ in Thousands					9 Months Ended
	Aug. 12, 2025 USD ($) ft²	Aug. 11, 2025 USD ($)	Jul. 16, 2025 USD ($) ft²	Jan. 15, 2025 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Jul. 15, 2025 USD ($)
Debt Instrument
Repayments of long-term debt					$ 1,900,683	$ 95,696
PENN 11
Debt Instrument
Debt amount							$ 500,000
Repayments of long-term debt			$ 50,000
Basis spread on variable rate (in percent)			2.06%
All-in swapped rate			6.28%
Proceeds from property refinancing			$ 130
4 Union Square South
Debt Instrument
Debt amount		$ 120,000
Basis spread on variable rate (in percent)		1.50%
Office | PENN 11
Debt Instrument
Stated rate (in percent)			6.35%
Debt amount			$ 450,000
Square footage of real estate property (in sqft) | ft²			1,200
Debt term			5 years
Office | 4 Union Square South
Debt Instrument
Stated rate (in percent)	5.64%
Debt amount	$ 120,000
Square footage of real estate property (in sqft) | ft²	204
Debt term	10 years
Senior Unsecured Notes Due 2025 | Unsecured Debt
Debt Instrument
Repaid on loan				$ 450,000
Stated rate (in percent)				3.50%