Deferred Costs, Acquired Lease Intangibles and Goodwill Narrative (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Deferred Costs [Line Items]
Amortization of deferred leasing costs	$ 2,400,000	$ 2,100,000	$ 4,800,000	$ 4,000,000
Amortization of deferred finance costs and debt premiums	1,400,000	1,900,000	2,500,000	3,500,000
Revenue related to amortization of acquired above- and below-market leases, net	2,000,000		3,900,000
Goodwill	491,479,000		491,479,000		491,479,000
Empire State Building Observatory Operations [Member]
Deferred Costs [Line Items]
Goodwill	227,500,000		227,500,000
Empire State Building, L.L.C. [Member]
Deferred Costs [Line Items]
Goodwill	250,800,000		250,800,000
501 Seventh Avenue Associates [Member]
Deferred Costs [Line Items]
Goodwill	13,200,000		13,200,000
Lease Agreements [Member]
Deferred Costs [Line Items]
Amortization expense related to acquired lease intangibles	$ 5,300,000	$ 0	$ 10,500,000	$ 0