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

No definition available.

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

- Definition

Represents the weighted average interest rate on notes payable during the period.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

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.

+ References

No definition available.

+ Details

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

- Definition

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

+ 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

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Maximum 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:	duration

- Definition

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

+ 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)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ 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)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Including the current and noncurrent portions, aggregate carrying amount of all types of notes payable, as of the balance sheet date, with initial maturities beyond one year or beyond the normal operating cycle, if longer.

+ References

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)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 13, 16
-Article 9

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 20, 22
-Article 5

+ Details

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

- Definition

The cash outflow for a borrowing supported by a written promise to pay an obligation.

+ References

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3291-108585

+ Details

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

- Details

Name:	us-gaap_LongtermDebtTypeAxis=eqr_A5.125NotesMember
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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Debt Notes (Details) - USD ($) $ in Thousands	3 Months Ended
Debt Notes (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Debt Instrument [Line Items]
Notes, net	$ 4,360,137		$ 5,848,956
Repayments of Notes Payable	1,500,000	$ 0
Write Off Of Unamortized Deferred Financing Costs	1,900
Write off unamortized premium discount	25,200
5.125% Notes [Member]
Debt Instrument [Line Items]
Repayments of Notes Payable	$ 228,900
Debt Instrument, Interest Rate, Stated Percentage	5.125%
Prepayment Penalty Charges	$ 1,400
5.375% Notes [Member]
Debt Instrument [Line Items]
Repayments of Notes Payable	$ 400,000
Debt Instrument, Interest Rate, Stated Percentage	5.375%
Prepayment Penalty Charges	$ 9,500
5.750% Notes [Member]
Debt Instrument [Line Items]
Repayments of Notes Payable	$ 255,900
Debt Instrument, Interest Rate, Stated Percentage	5.75%
Prepayment Penalty Charges	$ 16,500
7.125% Notes [Member]
Debt Instrument [Line Items]
Repayments of Notes Payable	$ 46,100
Debt Instrument, Interest Rate, Stated Percentage	7.125%
Prepayment Penalty Charges	$ 4,600
4.625% Notes [Member]
Debt Instrument [Line Items]
Repayments of Notes Payable	$ 250,000
Debt Instrument, Interest Rate, Stated Percentage	4.625%
Prepayment Penalty Charges	$ 31,600
7.570% Notes [Member]
Debt Instrument [Line Items]
Repayments of Notes Payable	$ 48,000
Debt Instrument, Interest Rate, Stated Percentage	7.57%
Prepayment Penalty Charges	$ 19,300
Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Jun. 01, 2045
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	2.375%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum	7.57%
Weighted Average Interest Rate	4.62%
Paid at Maturity [Member] \| 5.125% Notes [Member]
Debt Instrument [Line Items]
Repayments of Notes Payable	$ 271,100
Debt Instrument, Interest Rate, Stated Percentage	5.125%