Deferred Costs, Acquired Lease Intangibles and Goodwill Narrative (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Deferred Costs [Line Items]
Amortization of deferred leasing costs	$ 2,200,000	$ 2,400,000	$ 7,000,000	$ 6,400,000
Amortization of deferred finance costs and debt premiums	2,700,000	2,000,000	5,100,000	5,600,000
Revenue related to amortization of acquired above- and below-market leases, net	4,600,000		8,500,000
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	$ 10,100,000	$ 0	$ 20,700,000	$ 0