Carrying amount of equity interests owned by noncontrolling partners in partially owned properties.

No definition available.

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

- Definition

Represents the value of Noncontrolling Interest distributions had the Company's partnership agreements been liquidated through the sale of their assets upon reaching the date specified in each respective partnership agreement. The Company, as controlling partner, has an obligation to cause the property owning partnerships to distribute the proceeds of liquidation to the Noncontrolling Interests in these Partially Owned Properties.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

- Definition

A gain (loss) realized on a transfer, accounted for as a sale, of all or a portion of financial assets in which the transferor surrenders control and receives consideration other than a beneficial interest in the assets transferred. Reflects the amount of sales proceeds in excess of, or deficient from, the sum of the carrying amounts of transferred financial assets plus transaction costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.7,9)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

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

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a),(b)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32639-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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

- Definition

The number of real estate properties owned as of the balance sheet date.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of units in a real estate property owned as of the balance sheet date.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_RealEstatePropertiesAxis=us-gaap_ConsolidatedPropertiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RealEstatePropertiesAxis=eqr_LimitedLifePartnershipPropertiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AdjustmentsForNewAccountingPrincipleEarlyAdoptionMember
Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_IncomeTaxAuthorityAxis=us-gaap_DomesticCountryMember
Namespace Prefix:
Data Type:	na
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Period Type:

Summary of Significant Accounting Policies - Additional Information (Details)	1 Months Ended	3 Months Ended		6 Months Ended
	Feb. 28, 2017 USD ($)	Jun. 30, 2017 USD ($) Property ApartmentUnit	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) Property ApartmentUnit	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Provision for income tax		$ 220,000	$ 413,000	$ 482,000	$ 763,000
Properties \| Property		301		301
Apartment Units \| ApartmentUnit		77,034		77,034
Partially Owned Properties		$ 6,303,000		$ 6,303,000		$ 10,609,000
Partially Owned Properties – Consolidated
Properties \| Property		17		17
Apartment Units \| ApartmentUnit		3,215		3,215
Limited Life Partnership Properties [Member]
Properties \| Property		4		4
Partially Owned Properties		$ 7,400,000		$ 7,400,000
Noncontrolling Interests Settlement Value		$ 64,400,000		64,400,000
Adjustments for New Accounting Principle, Early Adoption
Gain (loss) on equity transaction	$ 0
Federal [Member]
Provision for income tax				$ 0