Aggregate approximate area of office buildings.

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- Definition

Committed Preferred Equity.

+ Details

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Balance Type:	credit
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- Definition

Initial contribution for acquisition of partnerships.

+ Details

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- Definition

Investment in Unconsolidated Ventures.

+ Details

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- Definition

Maximum Percentage of Unconsolidated Equity Method Investment Ownership.

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- Definition

Minimum percentage of unconsolidated equity method investment ownership.

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Data Type:	us-types:percentItemType
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- Definition

Net Rentable Space Sold.

+ Details

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Data Type:	us-types:areaItemType
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- Definition

Number of office buildings in Real Estate Ventures.

+ Details

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Balance Type:	na
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- Definition

Number of office buildings owned.

+ Details

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- Definition

Number of Partnership in which the Company acquired interest.

+ Details

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- Definition

Number of real estate ventures that owns buildings.

+ Details

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- Definition

Number of rooms contain in one real estate venture developed as Hotel Property.

+ Details

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- Definition

Number of unconsolidated investments in Real Estate Ventures.

+ Details

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- Definition

Percentage of interest acquired in partnerships.

+ Details

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- Definition

Percentage of interest acquired in partnerships by other partner.

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- Definition

Property occupied as of date of sale.

+ Details

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- Definition

Realized Gains Losses on Sales of Investment Real Estate.

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- Definition

Remaining portion of contribution.

+ Details

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- Definition

Sale Consideration Of Sold Property.

+ Details

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 18
-Subparagraph f

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 18
-Paragraph 20
-Subparagraph a (1)

+ Details

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Investment in Unconsolidated Ventures (Details Textuals 1) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2011 sqft	Dec. 31, 2012	Jul. 29, 2011 sqft	Nov. 30, 2010
Investment in Unconsolidated Ventures (Textuals) [Abstract]
Number of unconsolidated Real Estate Ventures	16
Number of office buildings owned by 14 Real Estate Ventures	49
Number of real estate ventures that owns 49 office buildings	14
Net rentable square feet of 49 office buildings owned the 14 Real Estate Ventures	6,100,000
Number of rooms in a hotel property developed by one Real Estate Venture	137
Minimum ownership interest in unconsolidated Real Estate Ventures	10.00%
Maximum ownership interest in unconsolidated Real Estate Ventures	65.00%
Percentage of interest acquired in partnerships				25.00%
Interest acquired in partnerships, Number				2
Number of office buildings owned				2
Percentage of interest acquired in partnerships by other partner				75.00%
Initial contribution for acquisition of partnerships				$ 5.0
Contribution for acquisition of partnerships				25.0
Remaining portion of contribution		20.0
Company's ownership percentage in the Real Estate Venture			3.00%
Net rentable square feet of properties sold			347,620
Sales price of properties sold			86.7
Gain on sale of ownership interest	$ 2.8
Property occupied as of date of sale	87.00%