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Equity, Capital and Other Interests - Changes in Operating Partnership's Issued and Outstanding Units (Details) - shares | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
General and Limited Partner Units |  |  |
Common Shares And Units Outstanding | 380,496,999 | 379,182,608 |
Exercise of share options | 846,137 | 815,044 | 1,456,363
Employee Share Purchase Plan (ESPP) | 68,286 | 63,909 | 68,462
Restricted share grants, net | 83,451 | 147,689 | 168,142
Restricted unit grants, net | 291,647 | 287,749 | 335,496
Common Shares And Units Outstanding | 381,786,520 | 380,496,999 | 379,182,608
LIMITED PARTNERS |  |  |
Total Units Outstanding | 14,626,075 | 14,427,164 | 14,298,691
Restricted unit grants, net | 291,647 | 287,749 | 335,496
Conversion of restricted shares to restricted units | 0 | 0 | 1,284
Conversion of Limited Partner OP Units to EQR Common Shares | (1,149,284) | (88,838) | (208,307)
Total Units Outstanding | 13,768,438 | 14,626,075 | 14,427,164
Units Ownership Interest in Operating Partnership | 3.60% | 3.80% | 3.80%
ERPOP [Member] |  |  |
General and Limited Partner Units |  |  |
Common Shares And Units Outstanding | 380,496,999 | 379,182,608 | 377,154,145
Exercise of share options | 846,137 | 815,044 | 1,456,363
Employee Share Purchase Plan (ESPP) | 68,286 | 63,909 | 68,462
Restricted share grants, net | 83,451 | 147,689 | 168,142
Restricted unit grants, net | 291,647 | 287,749 | 335,496
Common Shares And Units Outstanding | 381,786,520 | 380,496,999 | 379,182,608
LIMITED PARTNERS |  |  |
Total Units Outstanding | 14,626,075 | 14,427,164 | 14,298,691
Restricted unit grants, net | 291,647 | 287,749 | 335,496
Conversion of restricted shares to restricted units | 0 | 0 | 1,284
Conversion of Limited Partner OP Units to EQR Common Shares | (1,149,284) | (88,838) | (208,307)
Total Units Outstanding | 13,768,438 | 14,626,075 | 14,427,164
Units Ownership Interest in Operating Partnership | 3.60% | 3.80% | 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 long term incentive plan units issued during the period as a result of the conversion of restricted shares prior to vesting. + References No definition available. + Details
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Period Type: | duration

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- Definition Number of units issued during the period as a result of a long-term incentive plan. + References No definition available. + Details
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- Definition The number of restricted shares granted during the reporting period, net of cancellations. + References No definition available. + Details
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- Definition OP Units converted into shares of stock during the period. An example of a convertible unit is an umbrella partnership real estate investment trust unit (UPREIT unit). Subject to certain exceptions, this unit can be exchanged for Common Shares on a one-for-one basis. + References No definition available. + Details
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- Definition Units outstanding. + References No definition available. + Details
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- Definition Represents the noncontrolling interests (comprised of Units and LTIP Units) ownership interest in the Operating Partnership. + References No definition available. + Details
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- Definition Number of shares issued during the period as a result of an employee stock purchase plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21463-112644 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(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 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(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
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- Definition Number of share options (or share units) exercised during the current period. + 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(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21463-112644 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(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(2) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Details
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