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

The weighted average fair value as of the grant date of long term incentive plans that were not exercised during the reporting period as a result of occurrence of a terminating event specified in the contractual agreement.

No definition available.

Name:	eqr_ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanForfeitedWeightedAverageGrantDateFairValue
Namespace Prefix:	eqr_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

The number of long-term incentive plan units granted during the period under a long-term incentive plan.

No definition available.

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

The weighted average fair value at grant for nonvested long-term incentive plan units issued during the period.

No definition available.

Name:	eqr_ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanGrantsWeightedAverageGrantDateFairValue
Namespace Prefix:	eqr_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

The number of outstanding units under a long-term incentive plan at the balance sheet date for which the employee has not yet satisfied service or performance criteria necessary to gain title to the proceeds.

No definition available.

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

The weighted average fair value of nonvested long-term incentive plan units at the balance sheet date for which the employee who has not yet satisfied service or performance criteria to gain title.

No definition available.

Name:	eqr_ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanUnitsWeightedAverageGrantDateFairValue
Namespace Prefix:	eqr_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

The number (units) of long-term incentive plan units vested/exercised during the period.

No definition available.

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

The weighted average fair value for long-term incentive plan units vested/exercised during the period.

No definition available.

Name:	eqr_ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanVestedExercisedInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	eqr_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

The number of equity-based payment instruments, excluding stock (or unit) options that were expired during the reporting period.

No definition available.

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

The weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans in which the lapse of rights to exercise during the reporting period occurred in an event specified in the contractual agreement of the plan.

No definition available.

Name:	eqr_Sharebasedcompensationarrangementbysharebasedpaymentawardequityinstrumentsotherthanoptionsexpiredinperiodweightedaveragegrantdatefairvalue
Namespace Prefix:	eqr_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

The number (units) of long-term incentive plan units expired during the period.

No definition available.

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

The weighted average fair value for long-term incentive plan units expired during the period.

No definition available.

Name:	eqr_Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanexpiredinperiodweightedaveragegrantdatefairvalue
Namespace Prefix:	eqr_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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

Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(ii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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

The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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

The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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

Gross number of share options (or share units) granted during the period.

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

Number of options outstanding, including both vested and non-vested options.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(ii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

Weighted average price at which option holders acquired shares when converting their stock options into shares.

Name:	us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

Name:	us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

Name:	us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

Name:	us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-SubTopic 10
-Topic 505
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-2

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-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 3: http://fasb.org/us-gaap/role/ref/legacyRef
-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 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(02)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-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