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Equity, Capital and Other Interests Text (Details) (USD $) | 9 Months Ended | 3 Months Ended | 9 Months Ended |
--- | --- | --- | --- | ---
Sep. 30, 2014 | Mar. 31, 2013 Archstone Transaction [Member] | Sep. 30, 2014 Partially Owned Properties [Member] | Sep. 30, 2014 Enclave at Wellington [Domain]
Issuance of Common Shares |  | 34,468,085 |  |
Stock Issued During Period, Value, New Issues |  | $ 1,900,000,000 |  |
Average Price Per Common Share Issued |  | $ 55.99 |  |
Units Issued During Period New Issues |  | 34,468,085 |  |
Additional Common Shares Authorized | 13,000,000 |  |  |
Stock Repurchase Program, Number of Shares Authorized to be Repurchased | 13,000,000 |  |  |
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased | 12,968,760 |  |  |
Stock Repurchased And Retired | (31,240) |  |  |
Treasury Stock Acquired, Average Cost Per Share | $ 56.87 |  |  |
Value Of Stock Repurchased And Retired | 1,800,000 |  |  |
OP Units repurchased and retired | (31,240) |  |  |
Properties acquired | 4 |  | 1 |
Number of Units in Real Estate Property | 111,087 |  | 3,771 | 268
Land parcels acquired | 2 |  | 1 |
Payments to Acquire Interest in Subsidiaries and Affiliates | 5,500,000 |  |  |
(Increase To) Reduction Of Paid In Capital | 2,300,000 |  |  |
Reduction In Partially Owned Properties | 2,200,000 |  |  |
Reduction In Other Liabilities | $ 1,000,000 |  |  |

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