Name:	eqr_ConsolidatedProjectUnderDevelopmentCommitmentFund
Namespace Prefix:	eqr_
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

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.

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

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

No definition available.

Name:	eqr_VariousStagesOfDevelopmentDateMaturity
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

Name:	us-gaap_AccrualForEnvironmentalLossContingencies
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of loss contingency liability.