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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.

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Period Type:	duration

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

No definition available.

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

No definition available.

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Data Type:	num:perShareItemType
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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.

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Data Type:	xbrli:sharesItemType
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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.

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Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

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

No definition available.

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Data Type:	xbrli:sharesItemType
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The weighted average fair value for long-term incentive plan units vested/exercised during the period.

No definition available.

Name:	eqr_ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanVestedExercisedInPeriodWeightedAverageGrantDateFairValue
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Data Type:	num:perShareItemType
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Period Type:	duration

Special Dividend Adjustment to 2011 Share award plan. Increases total shares available for grant to account for the 2016 Special Dividend activity. This adjustment is cash neutral.

No definition available.

Name:	eqr_ShareBasedCompensationArrangementByShareBasedPaymentAwardSpecialDividendAdjustment
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Data Type:	xbrli:sharesItemType
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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
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Data Type:	xbrli:sharesItemType
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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
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Data Type:	num:perShareItemType
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The number (units) of long-term incentive plan units expired during the period.

No definition available.

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Data Type:	xbrli:sharesItemType
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The weighted average fair value for long-term incentive plan units expired during the period.

No definition available.

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Data Type:	num: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.

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

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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.

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Data Type:	num:perShareItemType
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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).

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Data Type:	xbrli:sharesItemType
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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).

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Data Type:	num:perShareItemType
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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.

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Data Type:	xbrli:sharesItemType
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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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

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Data Type:	xbrli:sharesItemType
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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.

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

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Data Type:	xbrli:sharesItemType
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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.

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Data Type:	xbrli:sharesItemType
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Gross number of share options (or share units) granted during the period.

No definition available.

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Data Type:	xbrli:sharesItemType
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Number of options outstanding, including both vested and non-vested options.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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

No definition available.

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

No definition available.

Name:	us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice
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Data Type:	num:perShareItemType
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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

No definition available.

Name:	us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
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Data Type:	num:perShareItemType
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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

No definition available.

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Data Type:	num:perShareItemType
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Number of share options (or share units) exercised during the current period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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