Name:	eqr_CapitalizedCostsDevelopmentAndRenovation
Namespace Prefix:	eqr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Carrying value of land and property after the effect of depreciation for Federal Income Tax purposes.

No definition available.

Name:	eqr_LandAndDepreciablePropertyNet
Namespace Prefix:	eqr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Represents the average term in months of In-place lease intangibles over which the asset is amortized.

No definition available.

Name:	eqr_LeaseIntangiblesAverageTerm
Namespace Prefix:	eqr_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Carrying amount of equity interests owned by noncontrolling partners in partially owned properties.

No definition available.

Name:	eqr_NoncontrollingInterestsPartiallyOwnedProperties
Namespace Prefix:	eqr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Represents the value of Noncontrolling Interest distributions had the Company's partnership agreements been liquidated through the sale of their assets upon reaching the date specified in each respective partnership agreement. The Company, as controlling partner, has an obligation to cause the property owning partnerships to distribute the proceeds of liquidation to the Noncontrolling Interests in these Partially Owned Properties.

No definition available.

Name:	eqr_NoncontrollingInterestsSettlementValue
Namespace Prefix:	eqr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Value of the maximum amount applied on a per apartment unit basis to estimate the fair value of furniture and fixtures inside the unit for newly acquired properties based on economic age.

No definition available.

Name:	eqr_ValueOfFurnitureAndFixturesMaximumRange
Namespace Prefix:	eqr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Value of the minimum amount applied on a per apartment unit basis to estimate the fair value of furniture and fixtures inside the unit for newly acquired properties based on economic age.

No definition available.

Name:	eqr_ValueOfFurnitureAndFixturesMinimumRange
Namespace Prefix:	eqr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Face amount or stated value per share of common stock.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Data Type:	num:perShareItemType
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Period Type:	instant

Term of the lessor's leasing arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_LessorLeasingArrangementsOperatingLeasesTermOfContract
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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

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

No definition available.

Name:	us-gaap_NumberOfRealEstateProperties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

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

No definition available.

Name:	us-gaap_NumberOfUnitsInRealEstateProperty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

No definition available.

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_LeaseArrangementTypeAxis=eqr_RetailCommercialLeasesMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_FurnitureAndFixturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingImprovementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=eqr_ReplacementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=eqr_RenovationsAndImprovementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RealEstatePropertiesAxis=us-gaap_UnconsolidatedPropertiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_RealEstatePropertiesAxis=us-gaap_ConsolidatedPropertiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
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