Employee Plans - Summary of Information Regarding the Common Shares Issued Under the ESPP (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Employee Service Share Based Compensation Aggregate Disclosures [Abstract]
Shares issued	70,702	90,196	48,131
Issuance price ranges, Minimum	$ 53.13	$ 46.23	$ 59.56
Issuance price ranges, Maximum	$ 71.04	$ 63.84	$ 72.91
Issuance proceeds	$ 4,265	$ 4,508	$ 3,116

Represents the maximum price that employees purchase common stock for under the employee purchase plan during the year.

No definition available.

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- Definition

Represents the minimum price that employees purchase common stock for under the employee purchase plan during the year.

+ References

No definition available.

+ Details

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Namespace Prefix:	eqr_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

+ Details

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- Definition

Amount of cash inflow from issuance of shares under share-based payment arrangement. Excludes option exercised.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3255-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=SL79508275-113901

+ Details

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

- Definition

Number of shares issued under share-based payment arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

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