Investments in Non-controlled Entities Schedule of Equity Method Investments (Details)	0 Months Ended	9 Months Ended
Oct. 06, 2013 entity	Sep. 30, 2014 entity	Sep. 30, 2013 Empire State Building, L.L.C. [Member]	Sep. 30, 2013 1333 Broadway Associates [Member]	Sep. 30, 2013 1350 Broadway Associates [Member]	Sep. 30, 2013 501 Seventh Avenue Associates [Member]
Schedule of Equity Method Investments [Line Items]
Number of entities acquired	4	4
Ownership percentage			23.75%	50.00%	50.00%	20.469%

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant