Investments in Unconsolidated Joint Ventures - Mortgages and Other Loans Payable (Details)	6 Months Ended
	Jun. 30, 2022 USD ($) ft² extension	Dec. 31, 2021 USD ($)
Debt Instrument [Line Items]
Total fixed rate debt	$ 835,875,000	$ 1,073,409,000
Total floating rate debt	690,148,000	361,051,000
Total fixed rate and floating rate debt	$ 1,526,023,000	1,434,460,000
Area of office building (sqft) | ft²	27,211,821
Joint venture
Debt Instrument [Line Items]
Total fixed rate debt	$ 8,011,465,000	8,216,666,000
Total floating rate debt	3,394,998,000	2,999,726,000
Total fixed rate and floating rate debt	11,406,463,000	11,216,392,000
Deferred financing costs, net	(117,871,000)	(130,516,000)
Total joint venture mortgages and other loans payable, net	$ 11,288,592,000	11,085,876,000
Joint venture | 717 Fifth Avenue
Debt Instrument [Line Items]
Economic Interest	10.92%
Ownership interest	10.92%
Area of office building (sqft) | ft²	119,500
Joint venture | 717 Fifth Avenue | Mortgage loan
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	4.45%
Total fixed rate debt	$ 300,000,000	300,000,000
Joint venture | 717 Fifth Avenue | Mezzanine loans
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	5.50%
Total fixed rate debt	$ 355,328,000	355,328,000
Joint venture | 650 Fifth Avenue
Debt Instrument [Line Items]
Economic Interest	50.00%
Ownership interest	50.00%
Area of office building (sqft) | ft²	69,214
Joint venture | 650 Fifth Avenue | Mortgage loan
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	4.46%
Total fixed rate debt	$ 210,000,000	210,000,000
Joint venture | 650 Fifth Avenue | Mezzanine loans
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	5.45%
Total fixed rate debt	$ 65,000,000	65,000,000
Joint venture | 21 East 66th Street
Debt Instrument [Line Items]
Economic Interest	32.28%
Interest rate, fixed rate debt (as a percent)	3.60%
Interest rate, floating rate debt (as a percent)	2.75%
Total fixed rate debt	$ 12,000,000	12,000,000
Total floating rate debt	$ 608,000	632,000
Ownership interest	32.28%
Area of office building (sqft) | ft²	13,069
Joint venture | 919 Third Avenue
Debt Instrument [Line Items]
Economic Interest	51.00%
Interest rate, fixed rate debt (as a percent)	5.12%
Total fixed rate debt	$ 500,000,000	500,000,000
Ownership interest	51.00%
Area of office building (sqft) | ft²	1,454,000
Joint venture | 1515 Broadway
Debt Instrument [Line Items]
Economic Interest	56.87%
Interest rate, fixed rate debt (as a percent)	3.93%
Total fixed rate debt	$ 792,137,000	801,845,000
Ownership interest	56.87%
Area of office building (sqft) | ft²	1,750,000
Joint venture | 11 Madison Avenue
Debt Instrument [Line Items]
Economic Interest	60.00%
Interest rate, fixed rate debt (as a percent)	3.84%
Total fixed rate debt	$ 1,400,000,000	1,400,000,000
Ownership interest	60.00%
Area of office building (sqft) | ft²	2,314,000
Joint venture | 800 Third Avenue
Debt Instrument [Line Items]
Economic Interest	60.52%
Interest rate, fixed rate debt (as a percent)	3.37%
Total fixed rate debt	$ 177,000,000	177,000,000
Ownership interest	60.52%
Area of office building (sqft) | ft²	526,000
Joint venture | Worldwide Plaza
Debt Instrument [Line Items]
Economic Interest	24.95%
Interest rate, fixed rate debt (as a percent)	3.98%
Total fixed rate debt	$ 1,200,000,000	1,200,000,000
Ownership interest	24.95%
Area of office building (sqft) | ft²	2,048,725
Joint venture | One Vanderbilt Avenue
Debt Instrument [Line Items]
Economic Interest	71.01%
Interest rate, fixed rate debt (as a percent)	2.95%
Total fixed rate debt	$ 3,000,000,000	3,000,000,000
Ownership interest	71.01%
Area of office building (sqft) | ft²	1,657,198
Joint venture | Stonehenge Portfolio
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)
Total fixed rate debt	$ 0	195,493,000
Joint venture | 280 Park Avenue
Debt Instrument [Line Items]
Economic Interest	50.00%
Interest rate, floating rate debt (as a percent)	1.73%
Total floating rate debt	$ 1,200,000,000	1,200,000,000
Ownership interest	50.00%
Area of office building (sqft) | ft²	1,219,158
Joint venture | 1552 Broadway
Debt Instrument [Line Items]
Economic Interest	50.00%
Interest rate, floating rate debt (as a percent)	2.65%
Total floating rate debt	$ 193,132,000	193,132,000
Ownership interest	50.00%
Area of office building (sqft) | ft²	57,718
Joint venture | 121 Greene Street
Debt Instrument [Line Items]
Economic Interest	50.00%
Interest rate, floating rate debt (as a percent)	2.00%
Total floating rate debt	$ 13,016,000	13,228,000
Ownership interest	50.00%
Area of office building (sqft) | ft²	7,131
Joint venture | 2 Herald Square
Debt Instrument [Line Items]
Economic Interest	51.00%
Interest rate, floating rate debt (as a percent)	1.95%
Total floating rate debt	$ 197,276,000	200,989,000
Ownership interest	51.00%
Area of office building (sqft) | ft²	369,000
Joint venture | 11 West 34th Street
Debt Instrument [Line Items]
Economic Interest	30.00%
Interest rate, floating rate debt (as a percent)	1.45%
Total floating rate debt	$ 23,000,000	23,000,000
Ownership interest	30.00%
Area of office building (sqft) | ft²	17,150
Joint venture | 220 East 42nd Street
Debt Instrument [Line Items]
Economic Interest	51.00%
Interest rate, floating rate debt (as a percent)	2.75%
Total floating rate debt	$ 510,000,000	510,000,000
Ownership interest	51.00%
Area of office building (sqft) | ft²	1,135,000
Joint venture | 115 Spring Street
Debt Instrument [Line Items]
Economic Interest	51.00%
Interest rate, floating rate debt (as a percent)	3.40%
Total floating rate debt	$ 65,550,000	65,550,000
Ownership interest	51.00%
Area of office building (sqft) | ft²	5,218
Joint venture | 100 Park Avenue
Debt Instrument [Line Items]
Economic Interest	49.90%
Interest rate, floating rate debt (as a percent)	2.25%
Total floating rate debt	$ 360,000,000	360,000,000
Ownership interest	49.90%
Area of office building (sqft) | ft²	834,000
Joint venture | 15 Beekman
Debt Instrument [Line Items]
Economic Interest	20.00%
Interest rate, floating rate debt (as a percent)	1.50%
Total floating rate debt	$ 61,531,000	43,566,000
Ownership interest	20.00%
Area of office building (sqft) | ft²	221,884
Joint venture | 15 Beekman | Construction Loans
Debt Instrument [Line Items]
Maximum facility capacity	$ 125,000,000
Joint venture | 10 East 53rd Street
Debt Instrument [Line Items]
Economic Interest	55.00%
Interest rate, floating rate debt (as a percent)	1.35%
Total floating rate debt	$ 220,000,000	220,000,000
Ownership interest	55.00%
Area of office building (sqft) | ft²	354,300
Joint venture | 450 Park Avenue
Debt Instrument [Line Items]
Economic Interest	25.10%
Interest rate, floating rate debt (as a percent)	2.10%
Total floating rate debt	$ 267,000,000	0
Ownership interest	50.10%
Area of office building (sqft) | ft²	337,000
Joint venture | One Madison Avenue
Debt Instrument [Line Items]
Economic Interest	25.50%
Interest rate, floating rate debt (as a percent)	3.35%
Total floating rate debt	$ 283,885,000	$ 169,629,000
Ownership interest	25.50%
Area of office building (sqft) | ft²	1,048,700
Joint venture | One Madison Avenue | Construction Loans
Debt Instrument [Line Items]
Maximum facility capacity	$ 1,250,000,000
Term	5 years
Number of extension options | extension	1
Period of extension options	1 year