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

Represents the amount by which available borrowings on the unsecured revolving credit facility was increased. The available borrowings may be increased by adding additional banks to the facility or obtaining the agreement of existing banks to increase their commitments.

No definition available.

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

Date when the line of credit is scheduled to be fully repaid, which may be presented in a variety of ways (year, month and year, day, quarter, etc.).

No definition available.

Name:	eqr_LineOfCreditMaturity
Namespace Prefix:	eqr_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	instant

Represents a spread that is dependent upon a credit rating or bids received from lenders and is blended with an interest rate for amounts borrowed under the credit facility.

No definition available.

Name:	eqr_LineOfCreditSpread
Namespace Prefix:	eqr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The weighted average interest rate on the revolving line of credit during the period.

No definition available.

Name:	eqr_WeightedAverageInterestRateRevolvingCreditFacility
Namespace Prefix:	eqr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Amount borrowed under the credit facility as of the balance sheet date.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

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

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

No definition available.

Name:	us-gaap_LineOfCreditFacilityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Net increase or decrease in the carrying amount of the credit facility for the period for reasons other than accrued, but unpaid interest, additional borrowings, repayments, and forgiveness.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 4

-Section 08

-Paragraph f

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.(f))

-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

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

- Details

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

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

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

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

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

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