Aggregate approximate area of office buildings.

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- Definition

Committed Preferred Equity.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Initial contribution for acquisition of partnerships.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Investment in Unconsolidated Ventures.

+ Details

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- Definition

Maximum Percentage of Unconsolidated Equity Method Investment Ownership.

+ Details

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- Definition

Minimum percentage of unconsolidated equity method investment ownership.

+ Details

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Data Type:	num:percentItemType
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- Definition

Net Rentable Space Sold.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
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- Definition

Number of office buildings in Real Estate Ventures.

+ Details

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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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Balance Type:	na
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- Definition

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

+ Details

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Data Type:	xbrli:integerItemType
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- Definition

Number of unconsolidated investments in Real Estate Ventures.

+ Details

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Data Type:	xbrli:integerItemType
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- Definition

Percentage of interest acquired in partnerships.

+ Details

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- Definition

Percentage of interest by other partner in acquired partnership.

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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.

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- Definition

Sale Consideration Of Sold Property.

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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

-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 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.

Reference 3: 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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Investment in Unconsolidated Ventures (Details Textuals 1) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
	Mar. 31, 2011	Sep. 30, 2011 Property Tenants Year sqft ac Room Buildings	Dec. 31, 2012	Jun. 29, 2011 sqft	Nov. 30, 2010 PartnershipUnit Buildings
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		20.00%
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%