Investments in Partially Owned Entities (512 West 22nd Street) (Details) - New York 512 West 22nd Street [Member] - Office Building [Member] ft² in Thousands, $ in Millions	Jun. 24, 2015 USD ($) ft²
Schedule Of Equity Method Investments [Line Items]
Equity method ownership percentage	55.00%
Square Footage Of Real Estate Property \| ft²	173
Estimated Development Cost	$ 235
Estimated Project Start Date	Fourth Quarter of 2015
Estimated Project Completion Date	2017

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant