The total number of rental properties that the Company disposed of to unaffiliated parties during the period.

No definition available.

Name:	eqr_DisposedProperties
Namespace Prefix:	eqr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Total number of rental units associated with rental properties that the company disposed of to unaffiliated third parties during the period.

+ References

No definition available.

+ Details

Name:	eqr_DisposedUnits
Namespace Prefix:	eqr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash inflow from the sale of real estate investment property.

+ References

No definition available.

+ Details

Name:	eqr_ProceedsFromSaleOfProperty
Namespace Prefix:	eqr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	eqr_RepaymentsOfMortgageNotesPayable
Namespace Prefix:	eqr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow or inflow for a financial contract that meets the hedge criteria as either a cash flow hedge, fair value hedge, or hedge of a net investment in a foreign operation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 27
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3581-108585

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-Name Accounting Standards Codification
-Topic 230
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-Section 45
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3098-108585

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3095-108585

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

+ References

No definition available.

+ Details

Name:	us-gaap_ProceedsFromDebtNetOfIssuanceCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Details

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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=eqr_ThreePointTwoFivePercentNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=eqr_FourPointZeroZeroPercentNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
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Subsequent Events - Additional Information (Details) $ in Thousands	1 Months Ended	6 Months Ended
	Aug. 03, 2017 USD ($) Property ApartmentUnit	Jun. 30, 2017 USD ($) Property ApartmentUnit	Jun. 30, 2016 USD ($)
Subsequent Event [Line Items]
Disposed Properties \| Property		3
Property Units disposed \| ApartmentUnit		904
Sales Price		$ 300,150
Repayment of mortgage debt		$ 6,971	$ 4,740
Subsequent Event [Member]
Subsequent Event [Line Items]
Repayment of mortgage debt	$ 90,000
Forward Starting Swaps [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Payments for (Proceeds from) Hedge, Investing Activities	1,300
3.25% Notes [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Public Notes, Face Value	$ 400,000
Debt Instrument, Interest Rate, Stated Percentage	3.25%
Proceeds from Debt, Net of Issuance Costs	$ 399,300
Debt Instrument, Interest Rate, Effective Percentage	3.30%
4.00% Notes [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Public Notes, Face Value	$ 300,000
Debt Instrument, Interest Rate, Stated Percentage	4.00%
Proceeds from Debt, Net of Issuance Costs	$ 293,200
Debt Instrument, Interest Rate, Effective Percentage	4.10%
Rental Properties – Consolidated
Subsequent Event [Line Items]
Disposed Properties \| Property		3
Property Units disposed \| ApartmentUnit		904
Sales Price		$ 266,700
Rental Properties – Consolidated \| Subsequent Event [Member]
Subsequent Event [Line Items]
Disposed Properties \| Property	1
Property Units disposed \| ApartmentUnit	120
Sales Price	$ 53,000