Name:	eqr_CommonSharesAndUnitsOutstanding
Namespace Prefix:	eqr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Number of units issued during the period as a result of a long-term incentive plan.

No definition available.

Name:	eqr_IssuanceOfLtips
Namespace Prefix:	eqr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Partners capital units shares repurchased and retired.

No definition available.

Name:	eqr_PartnersCapitalUnitsSharesRepurchasedAndRetired
Namespace Prefix:	eqr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

The number of restricted shares granted during the reporting period, net of cancellations.

No definition available.

Name:	eqr_RestrictedShareGrantsNet
Namespace Prefix:	eqr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

OP Units converted into shares of stock during the period. An example of a convertible unit is an umbrella partnership real estate investment trust unit (UPREIT unit). Subject to certain exceptions, this unit can be exchanged for Common Shares on a one-for-one basis.

No definition available.

Name:	eqr_SharesIssuedDuringPeriodSharesConversionOfUnitsToCommonShares
Namespace Prefix:	eqr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Units outstanding.

No definition available.

Name:	eqr_UnitsOutstanding
Namespace Prefix:	eqr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Represents the noncontrolling interests (comprised of Units and LTIP Units) ownership interest in the Operating Partnership.

No definition available.

Name:	eqr_UnitsOwnershipInterestInOperatingPartnership
Namespace Prefix:	eqr_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

Name:	us-gaap_GeneralAndLimitedPartnersCapitalAccountAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

Name:	us-gaap_LimitedPartnersCapitalAccountAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Number of shares issued during the period as a result of an employee stock purchase plan.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480070/505-10-S50-1

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480100/505-10-S45-3

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480100/505-10-S45-2

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477657/942-210-S45-1

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478478/942-210-S50-1

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(20))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(19))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480657/210-10-S50-11

Name:	us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Number of share options (or share units) exercised during the current period.