Name:	eqr_HistoricalCostOfEncumberedProperties
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Period Type:	instant

Represents the net premium/discount recorded as a result of the Company's mark-to-market calculation to determine fair value debt assumed in conjunction with an acquisition.

No definition available.

Name:	eqr_MarkToMarketDebtPremiums
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Balance Type:	credit
Period Type:	duration

Represents charges to interest expense related to the extinguishment of borrowing before maturity.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Number of properties collateralizing loans assumed from an acquisition.

No definition available.

Name:	eqr_PropertiesCollateralized
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Data Type:	xbrli:integerItemType
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Period Type:	duration

The cash outflow to repay long-term debt that is wholly or partially secured by collateral.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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Write-off of amounts previously capitalized as debt issuance costs as part of an extinguishment of debt.

No definition available.

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The weighted average interest rate on total mortgage debt for the period.

No definition available.

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The charge to earnings for the amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized in conjunction with early debt extinguishment.

No definition available.

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The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

No definition available.

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Contractual interest rate for funds borrowed, under the debt agreement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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-Subparagraph (SX 210.5-02.22(a)(1))

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Maximum contractual interest rate for funds borrowed, under the debt agreement.

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Minimum contractual interest rate for funds borrowed, under the debt agreement.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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The amount of debt that an Entity assumes in acquiring a business or in consideration for an asset received in a noncash (or part noncash) acquisition. Noncash is defined as transactions during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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Data Type:	xbrli:monetaryItemType
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The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

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Data Type:	xbrli:monetaryItemType
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Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5

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-Name Accounting Standards Codification

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-Subparagraph (SX 210.7-03.16)

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Balance Type:	credit
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Name:	us-gaap_DebtInstrumentAxis=us-gaap_SecuredDebtMember
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Name:	us-gaap_InvestmentTypeAxis=eqr_NewYorkLifeLoanMember
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Name:	us-gaap_LineOfCreditFacilityAxis=eqr_FannieMaePool3And4Domain
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Name:	us-gaap_LineOfCreditFacilityAxis=eqr_FannieMaePool3Domain
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