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Distribution Reinvestment Plan - Additional Information (Details) - shares | Dec. 31, 2017 | Sep. 30, 2014
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Distribution Reinvestment And Share Purchase Plan [Abstract] |  |
Common shares registered with distribution reinvestment and share purchase Plan (2011 DRIP) |  | 4,790,000
Number of shares available for issuance | 4,691,298 |

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- Definition Distribution Reinvestment and Share Purchase Plan. + References No definition available. + Details
Name: | eqr_DistributionReinvestmentAndSharePurchasePlanAbstract
Namespace Prefix: | eqr_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Represents the number of shares available for issuance under the company's dividend reinvestment plan at the balance sheet date. + References No definition available. + Details
Name: | eqr_NumberOfSharesAvailableForIssuance
Namespace Prefix: | eqr_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

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- Definition Represents the number of shares authorized for issuance under the company's dividend reinvestment plan at the registration date. + References No definition available. + Details
Name: | eqr_StockRegisteredDuringPeriodSharesDividendReinvestmentPlan
Namespace Prefix: | eqr_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant