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Investments In Unconsolidated Joint Ventures (Boston-Downtown Crossing) (Details) (Boston-Downtown Crossing [Member], USD $)
In Millions, unless otherwise specified |
0 Months Ended | 9 Months Ended | 12 Months Ended | 1 Months Ended | |||
|---|---|---|---|---|---|---|---|
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May 15, 2012
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Jan. 29, 2007
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Sep. 30, 2012
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Dec. 31, 2008
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Oct. 31, 2006
sqft
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Oct. 31, 2006
Maximum [Member]
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Oct. 31, 2006
Minimum [Member]
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| Schedule of Equity Method Investments [Line Items] | |||||||
| Area of office property, square feet | 1,200,000 | ||||||
| Percentage of interest in venture | 15.00% | ||||||
| Venture property acquisition cost | $ 100 | ||||||
| Internal rate of return | 15.00% | 10.00% | |||||
| Impairment of property | 69.5 | ||||||
| Optional purchase amount | $ 45 | ||||||
| Holding and distribution pattern under operating agreement | Distributions will generally be in proportion to its members' respective ownership interests and, depending upon the development unit, promotes will be available to specified partners after the achievement of certain internal rates of return ranging from 10 to 15 percent. | ||||||