Investment in Unconsolidated Joint Ventures Unconsolidated Joint Ventures (Details)	Sep. 30, 2013 sqft	Sep. 30, 2013 US Airways Building PKY W. Rio Salado, LLC sqft	Jun. 03, 2013 US Airways Building PKY W. Rio Salado, LLC sqft	Sep. 30, 2013 7000 Central Park 7000 Central Park JV LLC sqft	Sep. 16, 2013 7000 Central Park 7000 Central Park JV LLC	Sep. 11, 2013 7000 Central Park 7000 Central Park JV LLC sqft
Schedule of Equity Method Investments [Line Items]
Ownership percentage in equity investments (in percent)		74.58%		40.00%
Area of real estate property (in square feet)	640,000	225,000	225,000	415,000		415,000
Property occupied percentage	83.90%	100.00%			75.20%

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 Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 18

-Subparagraph f

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: 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

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 18

-Paragraph 20

-Subparagraph a (1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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