Name:	eqr_ConsolidatedProjectUnderDevelopmentCommitmentFund
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Total number of open development projects. May include projects that are held for and/or under development, completed and not stabilized or completed and stabilized. These projects are consolidated.

No definition available.

Name:	eqr_NumberOfProjectsInVariousStagesOfDevelopment
Namespace Prefix:	eqr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Number of properties with environmental reserves.

No definition available.

Name:	eqr_NumberOfPropertiesWithEnvironmentalReserves
Namespace Prefix:	eqr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Total number of unconsolidated open development projects. May include projects that are held for and/or under development, completed and not stabilized or completed and stabilized.

No definition available.

Name:	eqr_NumberOfUnconsolidatedProjects
Namespace Prefix:	eqr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Total number of units that are associated with open development projects. May include projects that are held for and/or under development, completed and not stabilized or completed and stabilized. These units are consolidated.

No definition available.

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Namespace Prefix:	eqr_
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Balance Type:	na
Period Type:	instant

Represents the latest completion date for the current projects under development.

No definition available.

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Namespace Prefix:	eqr_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

Total costs accrued as of the balance sheet date for environmental loss contingencies.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 25
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346

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The compensation expense recognized during the period pertaining to the deferred compensation arrangement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5047-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
-SubTopic 10
-Section 30
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20015-108363

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Period Type:	duration

Amount of loss contingency liability.

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Data Type:	xbrli:monetaryItemType
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Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77902758&loc=d3e41499-112717