Business - Additional Information (Details)	Sep. 30, 2021 State Property ApartmentUnit	Jul. 31, 2021 ApartmentUnit
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Number of states in which entity operates \| State	10
Properties \| Property	307
Apartment units	79,322
Washington D.C.
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Apartment units		162
ERPOP [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Noncontrolling interest, ownership percentage by parent	96.70%

Organization consolidation and presentation of financial statements disclosure.

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The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

No definition available.

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The number of real estate properties owned as of the balance sheet date.

No definition available.

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The number of states the entity operates in as of the balance sheet date.

No definition available.

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The number of units in a real estate property owned as of the balance sheet date.

No definition available.

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