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

No definition available.

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Data Type:	xbrli:monetaryItemType
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Represents the average term in months of In-place lease intangibles over which the asset is amortized.

No definition available.

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

No definition available.

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Balance Type:	credit
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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.

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Percentage of rental income excluded from accounting standard adoption.

No definition available.

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Percentage of rental income subject to accounting standard adoption.

No definition available.

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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.

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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.

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Data Type:	xbrli:monetaryItemType
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Face amount or stated value per share of common stock.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Description of assumptions and judgments used by lessee to determine discount rate for operating lease.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
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-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918673-209980

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Discount rate used by lessee to determine present value of operating lease payments.

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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 3
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-URI http://asc.fasb.org/extlink&oid=77888428&loc=SL77919359-209981

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Represents the quantification of the effect of adopting the new accounting standard or change in accounting principle expected by the entity to have a significant effect on the entity's financial statements.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

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

No definition available.

Name:	us-gaap_NumberOfRealEstateProperties
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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.

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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_RealEstatePropertiesAxis=us-gaap_ConsolidatedPropertiesMember
Namespace Prefix:
Data Type:	na
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Name:	us-gaap_RealEstatePropertiesAxis=eqr_LimitedLifePartnershipPropertiesMember
Namespace Prefix:
Data Type:	na
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Namespace Prefix:
Data Type:	na
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Name:	srt_RangeAxis=srt_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_LeaseArrangementTypeAxis=eqr_CorporateOfficeLeasesMember
Namespace Prefix:
Data Type:	na
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Name:	us-gaap_LeaseArrangementTypeAxis=eqr_GroundLeaseMember
Namespace Prefix:
Data Type:	na
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Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_FurnitureAndFixturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingImprovementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
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