Properties Held for Sale and Property Dispositions (Details) $ in Thousands	1 Months Ended												12 Months Ended
	Jul. 31, 2021 USD ($) ft²	Jun. 30, 2021 USD ($) ft²	Mar. 31, 2021 USD ($) ft²	Feb. 28, 2021 USD ($) ft²	Jan. 31, 2021 USD ($) ft²	Dec. 31, 2020 USD ($) ft²	Sep. 30, 2020 USD ($) ft²	May 31, 2020 USD ($) ft²	Mar. 30, 2020 USD ($)	Dec. 31, 2019 USD ($) ft²	Nov. 30, 2019 USD ($) ft²	Aug. 31, 2019 USD ($) ft²	Dec. 31, 2021 USD ($) ft²	Dec. 31, 2020 USD ($) ft²	Dec. 31, 2019 USD ($) ft²	Mar. 31, 2020 USD ($) ft²
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²													27,716,872
Employee-related liabilities						$ 0				$ 4,000			$ 1,400	$ 0	$ 4,000
Purchase price and other fair value adjustments													210,070	$ 187,522	$ 69,389
220 East 42nd Street | 220 East 42nd Street
Property Dispositions and Assets Held for Sale
Ownership percentage deconsolidated	51.00%
Investment fair value adjustment													206,800
1080 Amsterdam Avenue
Property Dispositions and Assets Held for Sale
Sales price													42,500
707 Eleventh Avenue
Property Dispositions and Assets Held for Sale
Charge in connection with classification to assets held for sale													15,000
Sales price													95,000
110 East 42nd Street
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²					215,400
Sales price					$ 117,100
Gain on Sale					$ 3,600
590 Fifth Avenue
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²					103,300
Sales price					$ 103,000
Gain on Sale					$ (3,200)
220 East 42nd Street
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²	1,135,000
Sales price	$ 783,500
Gain on Sale	$ 175,100
Ownership interest disposed	49.00%
635-641 Sixth Avenue
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²		267,000
Sales price		$ 325,000
Gain on Sale		$ 99,400
106 Spring Street
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²			5,928
Sales price			$ 35,000
Gain on Sale			$ (2,800)
133 Greene Street
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²				6,425
Sales price				$ 15,800
Gain on Sale				$ 200
712 Madison Avenue
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²					6,600
Sales price					$ 43,000
Gain on Sale					$ (1,400)
30 East 40th Street
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²						69,446								69,446
Sales price						$ 5,200								$ 5,200
Gain on Sale						$ (1,600)
1055 Washington Boulevard
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²						182,000								182,000
Sales price						$ 23,800								$ 23,800
Gain on Sale						$ (11,500)
Williamsburg Terrace
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²						52,000								52,000
Sales price						$ 32,000								$ 32,000
Gain on Sale						$ 11,800
410 Tenth Avenue
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²						638,000								638,000
Sales price						$ 952,500								$ 952,500
Gain on Sale						56,400
400 East 58th Street
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²							140,000
Sales price							$ 62,000
Gain on Sale							$ 8,300
609 Fifth Avenue - Retail Condominium
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²								21,437
Sales price								$ 168,000
Gain on Sale								$ 63,300
315 West 33rd Street - The Olivia
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²																492,987
Sales price																$ 446,500
Gain on Sale									$ 71,800
Suburban Properties
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²										1,107,000					1,107,000
Sales price										$ 229,200					$ 229,200
Gain on Sale										$ 1,800
1640 Flatbush Avenue
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²										1,000					1,000
Sales price										$ 16,200					$ 16,200
Gain on Sale										$ 5,500
562 Fifth Avenue
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²										42,635					42,635
Sales price										$ 52,400					$ 52,400
Gain on Sale										(26,600)
1010 Washington Boulevard (7)
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²											143,400
Sales price											$ 23,100
Gain on Sale											$ (7,100)
Impairment charge															7,100
Spring Street 115
Property Dispositions and Assets Held for Sale
Unaudited Approximate Usable Square Feet | ft²												5,218
Sales price												$ 66,600
Gain on Sale												$ 3,600
Ownership percentage in disposed asset												49.00%
Deconsolidation of ownership interest percentage												51.00%
Purchase price and other fair value adjustments												$ 3,800
Properties Sold In 2021, 2020 And 2019
Property Dispositions and Assets Held for Sale
Employee-related liabilities						$ 10,500				$ 2,000			$ 13,700	$ 10,500	$ 2,000