Fair Value Measurements (Schedule of Derivative Instruments) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Feb. 28, 2023	Dec. 31, 2022
Derivative [Line Items]
Long term debt	$ 2,562,574		$ 2,560,025
Matures in May 2028 | Five Five Five California Street | Office
Derivative [Line Items]
Equity method ownership percentage	70.00%		70.00%
Debt instrument, amount	$ 1,200,000		$ 1,200,000
Designated as Hedging Instrument | Interest Rate Cap
Derivative [Line Items]
Fair Value Asset	260,747		183,804
Designated as Hedging Instrument | 555 California Street Mortgage Loan, In-Place Swap | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance	$ 840,000
All-In Swapped Rate	2.29%
Fair Value Asset	$ 26,672		49,888
Designated as Hedging Instrument | 555 California Street Mortgage Loan, Forward Swap | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance	$ 840,000
All-In Swapped Rate	6.03%
Fair Value Asset	$ 6,627		0
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	$ 40,782		29,226
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	2.22%
Fair Value Asset	$ 11,305		26,587
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	3.87%
Fair Value Asset	$ 34,358		24,457
Designated as Hedging Instrument | Unsecured term loan | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance	$ 800,000
All-In Swapped Rate	4.04%
Fair Value Asset	$ 27,249		21,024
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	5.06%
Fair Value Asset	$ 16,907		6,886
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	$ 10,293		6,544
Long term debt	$ 63,400
Rate	7.13%
Designated as Hedging Instrument | 888 Seventh Avenue mortgage loan | Interest rate swaps | SOFR
Derivative [Line Items]
Derivative, basis spread on variable rate	1.80%
Designated as Hedging Instrument | 4 Union Square South mortgage loan | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance	$ 98,650
All-In Swapped Rate	3.74%
Fair Value Asset	$ 3,552		4,050
Long term debt	$ 21,350
Rate	6.83%
Designated as Hedging Instrument | 4 Union Square South mortgage loan | Interest rate swaps | SOFR
Derivative [Line Items]
Derivative, basis spread on variable rate	1.50%
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	70,599		7,590
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 | 1290 Avenue of the Americas mortgage loan | Interest Rate Cap | SOFR
Derivative [Line Items]
Cap strike rate	1.00%
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	$ 10,169		5,472
Designated as Hedging Instrument | One Park Avenue mortgage loan | Interest Rate Cap | SOFR
Derivative [Line Items]
Cap strike rate	3.89%
Designated as Hedging Instrument | One Park Avenue mortgage loan | Forward Cap | SOFR
Derivative [Line Items]
Cap strike rate	3.89%
Designated as Hedging Instrument | Various mortgage loans | Interest Rate Cap
Derivative [Line Items]
Fair Value Asset	$ 2,234		$ 2,080
Designated as Hedging Instrument | Unsecured Term Loan Expiring December 2027 | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance		$ 800,000
Designated as Hedging Instrument | Unsecured Term Loan Expiring October 2023 | Interest rate swaps
Derivative [Line Items]
Notional amount and swapped balance	$ 800,000
All-In Swapped Rate	4.04%
Unswapped Balance	$ 0
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	4.52%
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	$ 150,000
All-In Swapped Rate	4.35%
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	4.03%
Unswapped Balance	$ 750,000
Designated as Hedging Instrument | 1290 Avenue of Americas mortgage loan Expiring November 2025 | Interest Rate Cap | SOFR
Derivative [Line Items]
Cap strike rate	3.89%