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Equity, Capital and Other Interests ERP Units (Details) - shares | 9 Months Ended |
--- | --- | ---
Sep. 30, 2015 | Dec. 31, 2014
Capital Unit [Line Items] |  |
Common Shares And Units Outstanding | 378,595,767 |
Exercise of EQR share options | 882,764 |
EQR’s Employee Share Purchase Plan (ESPP) | 52,869 |
Restricted share grants, net | 168,484 |
Conversion of restricted shares to restricted units | (1,284) |
Conversion of Limited Partner OP Units to EQR Common Shares | 181,753 |
Units Ownership Interest in Operating Partnership | 3.80% |
ERPOP [Member] |  |
Capital Unit [Line Items] |  |
Common Shares And Units Outstanding | 378,595,767 | 377,154,145
Limited Partners' Capital Account, Units Outstanding | 14,455,727 | 14,298,691
Exercise of EQR share options | 882,764 |
EQR’s Employee Share Purchase Plan (ESPP) | 52,869 |
Restricted share grants, net | 168,484 |
Restricted units, net | 337,505 |
Conversion of restricted shares to restricted units | 1,284 |
Conversion of Limited Partner OP Units to EQR Common Shares | (181,753) |
Units Ownership Interest in Operating Partnership | 3.80% |

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- Definition Number of all classes of common stock held by shareholders, which is net of related treasury stock, and number of all Operating Partnership Units held by various individuals and entities that contributed their properties to the Operating Partnership. + References No definition available. + Details
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- Definition The number of limited partner units outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 5 -Subparagraph (SAB TOPIC 4.F) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 272 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70434-108055 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 4 -Section F + Details
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