- Definition

Date at which the registration statement to register shares for issuance under the company's dividend reinvestment plan became effective.

+ Details

Name:	eqr_DateOnWhichRegistrationStatementBecameEffective
Namespace Prefix:	eqr
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	instant

- Definition

Distribution Reinvestment and Share Purchase Plan.

+ Details

Name:	eqr_DistributionReinvestmentAndSharePurchasePlanTextualsAbstract
Namespace Prefix:	eqr
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of shares available for issuance under the company's dividend reinvestment plan at the balance sheet date.

+ Details

Name:	eqr_NumberOfSharesAvailableForIssuance
Namespace Prefix:	eqr
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Date on which registration statement related to the company's dividend reinvested plan expired and shares were no longer able to be issued.

+ Details

Name:	eqr_RegistrationStatementExpiryDate
Namespace Prefix:	eqr
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the discount from the market price which common shares may be purchased with optional cash payments made by participants in the dividend reinvested plan or new investors.

+ Details

Name:	eqr_ShareBasedCompensationArrangementByShareBasedPaymentDiscountFromMarketPrice
Namespace Prefix:	eqr
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the number of shares authorized for issuance under the company's dividend reinvestment plan outstanding at the registration date.

+ Details

Name:	eqr_StockRegisteredDuringPeriodSharesDividendReinvestmentPlan
Namespace Prefix:	eqr
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Distribution Reinvestment and Share Purchase Plan (Details)	Dec. 15, 2011	Dec. 31, 2010	Dec. 16, 2008	Nov. 25, 1997	Nov. 03, 1997
Distribution Reinvestment and Share Purchase Plan (Textuals) [Abstract]
Common Shares registered with Distribution Reinvestment and Share Purchase Plan (the "DRIP Plan")			5,000,000		14,000,000
Number of shares available for issuance		4,905,736
Date on which registration statement became effective			39798	35759
Registration statement, expiry date	Dec. 15, 2011
Discount range at which common shares can be purchased on a monthly basis with optional cash		0% and 5%