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Investments in Partially Owned Entities - Summary of Companys Investment in Unconsolidated Entities (Parenthetical) (Details) | 9 Months Ended
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Sep. 30, 2018 ApartmentUnit JointVenture
Variable Interest Entity [Line Items] |
Apartment units | 79,260
Operating Property [Member] | Unconsolidated Non-VIE [Member] |
Variable Interest Entity [Line Items] |
Apartment units | 945
Number of joint ventures under agreements | JointVenture | 2

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- Definition Number of joint ventures. + References No definition available. + Details
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Balance Type: | na
Period Type: | duration

X
- Definition The number of units in a real estate property owned as of the balance sheet date. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
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Balance Type: | na
Period Type: | duration

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- Details
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Namespace Prefix: |
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Balance Type: |
Period Type: |

X
- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |