Investments in Partially Owned Entities (One Park Avenue) (Details) (USD $)			0 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 26, 2014 One Park Avenue [Member]	Jun. 26, 2014 One Park Avenue [Member] Vornado Realty Trust [Member]	Dec. 31, 2013 One Park Avenue [Member] Vornado Realty Trust [Member]	Jun. 26, 2014 Joint venture, Canada Pension Plan Investment Board [Member] One Park Avenue [Member]
Schedule Of Equity Method Investments [Line Items]
Equity Method Investment Ownership, Additional Investment				$ 22,700,000
Equity method ownership percentage				55.00%	46.50%	45.00%
Aggregate fair value of Real Estate Fund investments (in US Dollars)	549,091,000	667,710,000	560,000,000
Mortgages payable (in US Dollars)	$ 8,988,843,000	$ 8,331,993,000	$ 250,000,000
Interest Rate, End of Period (in percentage)			4.995%
Maturity, Range, End			March 2016