Fair Value Measurements (Schedule of Derivative Instruments) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Jan. 31, 2024	Dec. 31, 2023
Derivative [Line Items]
Long term debt	$ 2,566,004		$ 2,563,432
Matures in May 2028 | 555 California Street | Office
Derivative [Line Items]
Equity method ownership percentage	70.00%		70.00%
Debt amount	$ 1,200,000		$ 1,200,000
Designated as Hedging Instrument
Derivative [Line Items]
Fair Value Asset	55,514		138,772
Fair Value Liability			7,239
Interest rate swaps and caps (included in other liabilities)	$ 11,510
Designated as Hedging Instrument | Interest rate swaps
Derivative [Line Items]
Unswapped Balance interest rate	1.30%
Designated as Hedging Instrument | 555 California Street mortgage loan | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance	$ 840,000
All-In Swapped Rate	6.03%
Fair Value Asset	$ 0		15,494
Fair Value Liability	6,575		6,091
Designated as Hedging Instrument | 770 Broadway mortgage loan | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance	$ 700,000
All-In Swapped Rate	4.98%
Fair Value Asset	$ 10,426		20,306
Fair Value Liability	0		0
Designated as Hedging Instrument | PENN 11 mortgage loan | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance	$ 500,000
All-In Swapped Rate	6.28%
Fair Value Asset	$ 0		4,702
Fair Value Liability	2,235		1,148
Designated as Hedging Instrument | Unsecured revolving credit facility | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance	$ 575,000
All-In Swapped Rate	3.88%
Fair Value Asset	$ 8,874		17,064
Fair Value Liability	0		0
Designated as Hedging Instrument | Unsecured term loan | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance	$ 700,000
All-In Swapped Rate	4.53%
Fair Value Asset	$ 3,764		11,089
Fair Value Liability	0		0
Designated as Hedging Instrument | 100 West 33rd Street mortgage loan | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance	$ 480,000
All-In Swapped Rate	5.26%
Fair Value Asset	$ 0		3,550
Fair Value Liability	1,215		0
Designated as Hedging Instrument | 888 Seventh Avenue mortgage loan | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance	$ 200,000
All-In Swapped Rate	4.76%
Fair Value Asset	$ 1,781		4,340
Fair Value Liability	0		0
Long term debt	$ 59,800
Derivative, basis spread on variable rate	1.80%
Variable interest rate	7.00%
Designated as Hedging Instrument | 4 Union Square South mortgage loan | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance	$ 96,850
All-In Swapped Rate	3.74%
Fair Value Asset	$ 596		2,327
Fair Value Liability	0		0
Long term debt	$ 23,150
Derivative, basis spread on variable rate	1.50%
Variable interest rate	6.70%
Designated as Hedging Instrument | 435 Seventh Avenue mortgage loan | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance	$ 75,000
All-In Swapped Rate	6.96%
Fair Value Asset	$ 0		0
Fair Value Liability	1,485		0
Designated as Hedging Instrument | 1290 Avenue of the Americas mortgage loan | Interest Rate Cap
Derivative [Line Items]
Notional amount and swapped balance	950,000
Fair Value Asset	28,747		53,784
Fair Value Liability	$ 0		0
Cap strike rate	1.00%
Premium paid in connection with the purchase of cap arrangement	$ 63,100
Designated as Hedging Instrument | 1290 Avenue of the Americas mortgage loan | Interest Rate Cap | Non-controlling Interests in Consolidated Subsidiaries
Derivative [Line Items]
Premium paid in connection with the purchase of cap arrangement	18,930
Designated as Hedging Instrument | One Park Avenue mortgage loan | Interest Rate Cap
Derivative [Line Items]
Notional amount and swapped balance	525,000
Fair Value Asset	1,307		5,297
Fair Value Liability	$ 0		0
Cap strike rate	3.89%
Designated as Hedging Instrument | Various mortgage loans | Interest Rate Cap
Derivative [Line Items]
Fair Value Asset	$ 19		819
Fair Value Liability	0		$ 0
Designated as Hedging Instrument | PENN 11 mortgage loan, Interest rate swap | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance		$ 250,000
Designated as Hedging Instrument | PENN 11 mortgage loan, In-Place Swap | Interest rate swaps
Derivative [Line Items]
All-In Swapped Rate		6.28%
Long term debt		$ 500,000
Designated as Hedging Instrument | Unsecured Term Loan Expiring July 2025 | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance	$ 700,000
All-In Swapped Rate	4.53%
Unswapped Balance	$ 100,000
Designated as Hedging Instrument | Unsecured Term Loan Expiring October 2026 | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance	$ 550,000
All-In Swapped Rate	4.36%
Unswapped Balance	$ 250,000
Designated as Hedging Instrument | Unsecured Term Loan Expiring August 2027 | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance	$ 50,000
All-In Swapped Rate	4.04%
Unswapped Balance	$ 750,000