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Consolidation and Basis of Presentation and Significant Accounting Policies - Additional Information (Detail) ft² in Thousands, $ in Thousands | 6 Months Ended |
--- | --- | ---
Jun. 30, 2017 USD ($) ft² Property States Communities shares | Jun. 30, 2016 shares
Real Estate Properties [Line Items] |  |
General Partners' Capital Account, Units Outstanding | shares | 113,607,734 | 75,524,086
Limited Liability (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest | 0.9642203707 |
Number of owned or owned interests of apartment communities | Property | 305 |
Number of states in which apartment units are located | States | 16 |
Percentage Of Ownership Interests | 100.00% |
Minimum [Member] |  |
Real Estate Properties [Line Items] |  |
Percentage Of Ownership Interests | 93.00% |
Maximum [Member] |  |
Real Estate Properties [Line Items] |  |
Percentage Of Ownership Interests | 100.00% |
Development Properties [Member] |  |
Real Estate Properties [Line Items] |  |
Number of owned or owned interests of apartment communities | Communities | 6 |
Number of units under development community | Property | 1,766 |
Development Properties [Member] | Expected Costs [Member] |  |
Real Estate Properties [Line Items] |  |
Development and capital improvements in progress | $ 396,100 |
Development Properties [Member] | Costs Incurred to Date [Member] |  |
Real Estate Properties [Line Items] |  |
Development and capital improvements in progress | $ 293,100 |
Retail |  |
Real Estate Properties [Line Items] |  |
Number of owned or owned interests of apartment communities | Property | 29 |
Square Footage of Real Estate Property | ft² | 600 |
Commercial Real Estate [Member] |  |
Real Estate Properties [Line Items] |  |
Square Footage of Real Estate Property | ft² | 269 |
Apartment Building [Member] |  |
Real Estate Properties [Line Items] |  |
Number of owned or owned interests of apartment communities | Communities | 304 |
Secured Debt [Member] | $750 million unsecured revolving credit facility [Member] | Fair Market Value Adjustment and Debt Issuance Cost [Member] |  |
Real Estate Properties [Line Items] |  |
Debt Instrument, Face Amount | $ (26,944) |
Post Massachusetts Avenue [Member] |  |
Real Estate Properties [Line Items] |  |
Equity Method Investment, Ownership Percentage | 35.00% |
Real Estate Investments, Joint Ventures | $ 44,800 |
Post River North [Member] |  |
Real Estate Properties [Line Items] |  |
Number of apartments included in a community | 358 |
Development and capital improvements in progress | $ 51,600 |
Percentage Of Ownership Interests | 92.50% |
Land | $ 14,500 |
Accrued expenses and other liabilities | $ 5,800 |

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