Investment in Unconsolidated Joint Ventures (Details) (USD $)	3 Months Ended																																1 Months Ended
	Mar. 31, 2014 investment sqft	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2014 21 East 66th Street sqft		Mar. 31, 2014 21 East 66th Street Three retail units unit	Mar. 31, 2014 21 East 66th Street 2 residential units unit	Mar. 31, 2014 21 East 66th Street Four residential units unit	Mar. 31, 2014 521 Fifth Avenue sqft		Mar. 31, 2014 100 Park Avenue sqft		Mar. 31, 2014 717 Fifth Avenue sqft		Mar. 31, 2014 800 Third Avenue sqft		Mar. 31, 2014 1745 Broadway sqft		Mar. 31, 2014 1 and 2 Jericho Plaza sqft		Mar. 31, 2014 The Meadows sqft		Mar. 31, 2014 388 and 390 Greenwich Street sqft		Mar. 31, 2014 180/182 Broadway sqft		Mar. 31, 2014 600 Lexington Avenue sqft		Mar. 31, 2014 11 West 34th Street sqft		Mar. 31, 2014 7 Renaissance sqft		Sep. 30, 2012 3 Columbus Circle	Mar. 31, 2014 3 Columbus Circle sqft		Mar. 31, 2014 280 Park Avenue sqft		Mar. 31, 2014 1552-1560 Broadway sqft		Dec. 31, 2013 1552-1560 Broadway sqft	Mar. 31, 2014 747 Madison Avenue sqft		Sep. 30, 2013 747 Madison Avenue unit	Mar. 31, 2014 747 Madison Avenue Joint Venture	Mar. 31, 2014 724 Fifth Avenue sqft		Mar. 31, 2014 10 East 53rd Street sqft		Mar. 31, 2014 33 Beekman sqft floor		Mar. 31, 2014 315 West 36th Street sqft		Mar. 31, 2014 650 Fifth Avenue sqft
General information on each joint venture
Number of VIEs in which the entity is not primary beneficiary (investments)	5
Net equity investment in VIEs in which the entity is not primary beneficiary	$ 315,300,000		$ 310,700,000
Ownership Interest (as a percent)				32.28%	[1]	32.28%		16.14%	50.50%		49.90%		10.92%		42.95%		32.26%		20.26%		50.00%		50.60%	[2]	25.50%		55.00%		30.00%		50.00%			48.90%	[3]	50.00%		50.00%	[4]		33.33%	[5]		100.00%	50.00%		55.00%		45.90%	[6]	35.50%		50.00%	[7]
Economic Interest (as a percent)				32.28%	[1]				50.50%		49.90%		10.92%		42.95%		32.26%		20.26%		50.00%		50.60%	[2]	25.50%		55.00%		30.00%		50.00%			48.90%	[3]	49.50%		50.00%	[4]		33.33%	[5]			50.00%		55.00%		45.90%	[6]	35.50%		50.00%	[7]
Area of property (sqft)	34,299,788			17,000	[1]				460,000		834,000		120,000		526,000		674,000		640,000		582,000		2,600,000	[2]	71,000		304,000		17,000		37,000			769,000	[3]	1,237,000		49,000	[4]	13,045	10,000	[5]			65,000		390,000		145,000	[6]	148,000		32,000	[7]
Acquisition Price				75,000,000	[1],[8]				315,000,000	[8]	95,800,000	[8]	251,900,000	[8]	285,000,000	[8]	520,000,000	[8]	210,000,000	[8]	111,500,000	[8]	1,575,000,000	[2],[8]	43,600,000	[8]	193,000,000	[8]	10,800,000	[8]	4,000,000	[8]		500,000,000	[3],[8]	400,000,000	[8]	136,550,000	[4],[8]		66,250,000	[5],[8]			223,000,000	[8]	252,500,000	[8]	31,000,000	[6],[8]	45,000,000	[8]	0	[7],[8]
Recognized gain (loss) on sale of interest in property	$ 104,640,000	$ 0																															$ 0
Number of units in property (units)						3	2	4																																			5
Number of floors of student housing (floors)																																																	30

[1] We hold a 32.28% interest in three retail and two residential units at the property and a 16.14% in four residential units at the property.

[2] The property is leased to a single tenant under a triple-net lease arrangement, which expires in December 2035. The tenant also has an option to acquire the property for a specified price during the period from December 1, 2017 through December 31, 2020. In March 2014, we entered into a contract to acquire our partner's interest in the joint venture. See Note 18, "Commitments and Contingencies" for related disclosure.

[3] As a result of the sale of a condominium interest in September 2012, Young & Rubicam, Inc., or Y&R, owns a portion of the property, generally floors three through eight referred to as Y&R units. Because the joint venture has an option to repurchase the Y&R units, no gain was recognized on this sale.

[4] The purchase price pertained only to the purchase of the 1552 Broadway interest which comprised 13,045 square feet. The joint venture also owns a long-term leasehold interest in the retail space and certain other spaces at 1560 Broadway, which is adjacent to 1552 Broadway.

[5] The joint venture owns 100% interest as tenant-in-common in 30 East 65th Street Corporation and the related proprietary lease of five cooperative apartment units in the building.

[6] The joint venture owns a fee interest in the property and will develop an approximately 30 story building for student housing. Upon completion of the development, the joint venture will convey a long-term ground lease condominium interest in the building to Pace.

[7] The joint venture owns a long-term leasehold interest in the retail space at 650 Fifth Avenue. In connection with the ground lease obligation, SLG provided a performance guaranty and Sutton executed a contribution agreement to reflect its pro rata obligation. In the event the property is converted into a condominium unit and the landlord elects the purchase option, the joint venture shall be obligated to acquire the unit at the then fair value.

[8] Acquisition price represents the actual or implied gross purchase price for the joint venture.