XML 56 R38.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Business - Additional Information (Details) | Sep. 30, 2017 State Property ApartmentUnit
--- | ---
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items] |
Number of States in which Entity Operates | State | 10
Properties | Property | 305
Apartment Units | ApartmentUnit | 78,302
ERPOP [Member] |
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items] |
Noncontrolling Interest, Ownership Percentage by Parent | 96.40%

X
- Definition Organization consolidation and presentation of financial statements disclosure. + References No definition available. + Details
Name: | eqr_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems
Namespace Prefix: | eqr_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The parent entity's interest in net assets of the subsidiary, expressed as a percentage. + References No definition available. + Details
Name: | us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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

X
- Definition The number of states the entity operates in as of the balance sheet date. + References No definition available. + Details
Name: | us-gaap_NumberOfStatesInWhichEntityOperates
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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

X
- Details
Name: | dei_LegalEntityAxis=eqr_ERPOPMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |