Fair Value Measurements (Summary of Derivative Instruments) (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2022	Dec. 31, 2021	Jul. 22, 2022	Jun. 28, 2022
Matures in May 2028 | Office | 555 California Street
Derivative [Line Items]
Equity method ownership percentage	70.00%	70.00%
Debt instrument, amount	$ 1,200,000,000	$ 1,200,000,000
Matures in July 2027 | 770 Broadway
Derivative [Line Items]
Debt instrument, amount				$ 700,000,000
Debt instrument, face amount, swapped to fixed interest rate				$ 350,000,000
Debt instrument, interest rate, stated percentage (percent)				5.11%
Interest rate, effective percentage	3.75%
Matures in July 2027 | 770 Broadway | Subsequent Event
Derivative [Line Items]
Debt instrument, face amount, swapped to fixed interest rate			$ 350,000,000
Debt instrument, interest rate, stated percentage (percent)			4.85%
Interest rate, effective percentage			4.98%
Interest rate swaps | Other liabilities | Designated as Hedging Instrument
Derivative [Line Items]
Derivative Liability, Fair Value		32,837,000
Derivative liability, notional amount		850,000,000
Interest rate swaps | 555 California Mortgage Loan Interest Rate Swap | Other Assets | Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Fair Value	$ 42,763,000	11,814,000
Derivative Asset, Notional Amount	$ 840,000,000	$ 840,000,000
Derivative, Interest Rate	3.26%	2.04%
Derivative, swap rate	2.26%	2.26%
Interest rate swaps | 555 California Mortgage Loan Interest Rate Swap | Other liabilities | Designated as Hedging Instrument
Derivative [Line Items]
Derivative expiration date	2024-05	2024-05
Interest rate swaps | PENN 11 mortgage loan interest rate swap | Other Assets | Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Fair Value	$ 23,609,000	$ 6,565,000
Derivative Asset, Notional Amount	$ 500,000,000	$ 500,000,000
Derivative, Interest Rate	3.07%	2.05%
Derivative, swap rate	2.23%	2.23%
Derivative expiration date	2024-03	2024-03
Interest rate swaps | Unsecured term loan | Other Assets | Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Fair Value	$ 2,497,000
Derivative Asset, Notional Amount	$ 750,000,000
Derivative, Interest Rate	2.83%
Derivative, swap rate	4.05%
Derivative expiration date	2023-10
Interest rate swaps | Unsecured term loan | Other liabilities | Designated as Hedging Instrument
Derivative [Line Items]
Derivative Liability, Fair Value		$ 28,976,000
Derivative liability, notional amount		$ 750,000,000
Derivative, Interest Rate		1.10%
Derivative, swap rate		3.87%
Derivative expiration date		2023-10
Interest rate swaps | 4 Union Square South mortgage loan | Other Assets | Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Fair Value	$ 1,613,000
Derivative Asset, Notional Amount	$ 100,000,000
Derivative, Interest Rate	2.46%
Derivative, swap rate	3.74%
Derivative expiration date	2025-01
Interest rate swaps | 770 Broadway | Other liabilities | Designated as Hedging Instrument
Derivative [Line Items]
Derivative Liability, Fair Value	$ 1,756,000
Derivative liability, notional amount	$ 350,000,000
Derivative, Interest Rate	3.75%
Derivative, swap rate	5.11%
Derivative expiration date	2027-07
Interest rate swaps | 33-00 Northern Boulevard mortgage loan interest rate swap | Other liabilities | Designated as Hedging Instrument
Derivative [Line Items]
Derivative Liability, Fair Value		$ 3,861,000
Derivative liability, notional amount		$ 100,000,000
Derivative, Interest Rate		1.91%
Derivative, swap rate		4.14%
Derivative expiration date		2025-01
Interest rate swaps | Secured Overnight Financing Rate (SOFR) | Unsecured term loan | Other Assets | Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Basis Spread on Variable Rate	0.013%
Interest rate swaps | Secured Overnight Financing Rate (SOFR) | 770 Broadway | Other liabilities | Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Basis Spread on Variable Rate	0.0225%
Interest rate swaps | LIBOR | 555 California Mortgage Loan Interest Rate Swap | Other Assets | Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Basis Spread on Variable Rate	0.0193%	0.0193%
Interest rate swaps | LIBOR | PENN 11 mortgage loan interest rate swap | Other Assets | Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Basis Spread on Variable Rate	0.0195%	0.0195%
Interest rate swaps | LIBOR | Unsecured term loan | Other liabilities | Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Basis Spread on Variable Rate		0.01%
Interest rate swaps | LIBOR | 4 Union Square South mortgage loan | Other Assets | Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Basis Spread on Variable Rate	0.014%
Interest rate swaps | LIBOR | 33-00 Northern Boulevard mortgage loan interest rate swap | Other liabilities | Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Basis Spread on Variable Rate		0.018%
Interest Rate Cap | Other Assets | Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Fair Value	$ 74,039,000	$ 18,929,000
Derivative Asset, Notional Amount	3,840,000,000	2,990,000,000
Interest Rate Cap | Various interest rate caps | Other Assets | Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Fair Value	3,557,000	550,000
Derivative Asset, Notional Amount	1,650,000,000	1,650,000,000
Floating | Interest rate swaps | Unsecured term loan | Other liabilities | Designated as Hedging Instrument
Derivative [Line Items]
Derivative liability, notional amount	50,000,000	$ 50,000,000
Floating | Interest rate swaps | 4 Union Square South mortgage loan | Other Assets | Designated as Hedging Instrument
Derivative [Line Items]
Derivative liability, notional amount	$ 20,000,000
Derivative, Basis Spread on Variable Rate	1.40%
Floating | Interest rate swaps | Secured Overnight Financing Rate (SOFR) | Unsecured term loan | Other liabilities | Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Basis Spread on Variable Rate	1.30%	1.30%