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Business Combinations Textual (Details) |  | 9 Months Ended |
--- | --- | --- | ---
Dec. 01, 2016 USD ($) ft² Communities properties $ / shares shares | Sep. 30, 2017 USD ($) Communities shares | Dec. 31, 2016 shares
Business Acquisition [Line Items] |  |  |
Embedded Derivative, Fair Value of Embedded Derivative Asset | $ 10,800,000 | $ 18,190,000 |
Business Combinations, Other Consideration | 2,000,000 |  |
Preferred Stock, Shares Outstanding | shares |  | 867,846 |
Business Combination, Separately Recognized Transactions [Domain] |  |  |
Business Acquisition [Line Items] |  |  |
Business Combination, Merger and Integration Related Expenses |  | $ 14,500,000 |
Unsecured Debt [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Business Combination, Consideration Transferred, Other | 300,000,000 |  |
Redeemable Preferred Stock [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Mandatorily Redeemable Preferred Stock, Fair Value Disclosure | 77.00 |  |
Embedded Derivative, Fair Value of Embedded Derivative Asset | $ 14.24 |  |
Preferred Stock, Shares Outstanding | shares | 867,846 |  |
Line of Credit [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Business Combination, Consideration Transferred, Other | $ 162,000,000 |  |
Parent Company [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Preferred Stock, Shares Outstanding | shares |  | 867,846 | 867,846
Parent Company [Member] | Post [Member] [Domain] |  |  |
Business Acquisition [Line Items] |  |  |
Number of Apartment Communities Acquired in Real Estate Property | Communities | 61 |  |
Number Of Units Acquired In Real Estate Property | Communities | 24,138 |  |
Number of Commercial Properties Acquired in Real Estate Property | properties | 4 |  |
Business Acquisition, Cost of Entity Acquired, Purchase Price | $ 4,000,000,000 |  |
Share Price | $ / shares | $ 91.41 |  |
Stock Issued During Period, Shares, Acquisitions | shares | 38,000,000 |  |
Equity Method Investments [Member] | Post [Member] [Domain] |  |  |
Business Acquisition [Line Items] |  |  |
Number Of Units Acquired In Real Estate Property | Communities | 269 |  |
Development Portfolio [Member] | Post [Member] [Domain] |  |  |
Business Acquisition [Line Items] |  |  |
Number Of Units Acquired In Real Estate Property | Communities | 2,262 |  |
Commercial [Member] | Parent Company [Member] | Post [Member] [Domain] |  |  |
Business Acquisition [Line Items] |  |  |
Square Footage of Real Estate Property | ft² | 232,000 |  |
Noncontrolling Interest [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Stock Issued During Period, Shares, Acquisitions | shares | 80,000 |  |
Post Massachusetts Avenue [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Number of Apartment Communities Acquired in Real Estate Property | Communities |  | 1 |

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