Equity, Capital and Other Interests - Changes in Operating Partnership's Issued and Outstanding Units (Details)	3 Months Ended
	Mar. 31, 2018 shares
General and Limited Partner Units
Exercise of share options	45,391
Employee Share Purchase Plan (ESPP)	35,177
Restricted share grants, net	108,261
Restricted unit grants, net	263,048
Common Shares And Units Outstanding	382,238,397
LIMITED PARTNERS
Total Units Outstanding	13,768,438
Restricted unit grants, net	263,048
Conversion of Limited Partner OP Units to EQR Common Shares	(5,000)
Total Units Outstanding	14,026,486
Units Ownership Interest in Operating Partnership	3.70%
ERPOP [Member]
General and Limited Partner Units
Common Shares And Units Outstanding	381,786,520
Exercise of share options	45,391
Employee Share Purchase Plan (ESPP)	35,177
Restricted share grants, net	108,261
Restricted unit grants, net	263,048
Common Shares And Units Outstanding	382,238,397
LIMITED PARTNERS
Total Units Outstanding	13,768,438
Restricted unit grants, net	263,048
Conversion of Limited Partner OP Units to EQR Common Shares	(5,000)
Total Units Outstanding	14,026,486
Units Ownership Interest in Operating Partnership	3.70%