Equity, Capital and Other Interests - Changes in Operating Partnership's Issued and Outstanding Units (Details) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
General and Limited Partner Units
Exercise of share options	709,071	45,391
Employee Share Purchase Plan (ESPP)	18,901	35,177
Restricted share grants, net	144,390	108,261
Restricted unit grants, net	133,214	263,048
Common Shares And Units Outstanding	384,314,772	382,238,397
LIMITED PARTNERS
Total Units Outstanding	13,904,035	13,768,438
Restricted unit grants, net	133,214	263,048
Conversion of Limited Partner OP Units to EQR Common Shares	(184,878)	(5,000)
Total Units Outstanding	13,852,371	14,026,486
Units Ownership Interest in Operating Partnership	3.60%	3.70%
ERPOP [Member]
General and Limited Partner Units
Common Shares And Units Outstanding	383,309,196	381,786,520
Exercise of share options	709,071	45,391
Employee Share Purchase Plan (ESPP)	18,901	35,177
Restricted share grants, net	144,390	108,261
Restricted unit grants, net	133,214	263,048
Common Shares And Units Outstanding	384,314,772	382,238,397
LIMITED PARTNERS
Total Units Outstanding	13,904,035	13,768,438
Restricted unit grants, net	133,214	263,048
Conversion of Limited Partner OP Units to EQR Common Shares	(184,878)	(5,000)
Total Units Outstanding	13,852,371	14,026,486
Units Ownership Interest in Operating Partnership	3.60%	3.70%