Equity, Capital and Other Interests - Changes in Operating Partnership's Issued and Outstanding General Partner Units and Limited Partner Units (Details) - shares	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
General and Limited Partner Units
Exercise of share options	219,922	1,430,048
Employee Share Purchase Plan (ESPP)	69,986	37,263
Restricted share grants, net	178,720	160,460
Restricted unit grants, net	247,822	140,055
Common Shares And Units Outstanding	386,118,649	385,077,022
Limited Partner Units
Total Units Outstanding	13,731,315	13,904,035
Restricted unit grants, net	247,822	140,055
Conversion of Limited Partner OP Units to EQR Common Shares	(99,737)	(294,400)
Total Units Outstanding	13,879,400	13,749,690
Units Ownership Interest in Operating Partnership	3.60%	3.60%
ERPOP [Member]
General and Limited Partner Units
Common Shares And Units Outstanding	385,402,199	383,309,196
Exercise of share options	219,922	1,430,048
Employee Share Purchase Plan (ESPP)	69,986	37,263
Restricted share grants, net	178,720	160,460
Restricted unit grants, net	247,822	140,055
Common Shares And Units Outstanding	386,118,649	385,077,022
Limited Partner Units
Total Units Outstanding	13,731,315	13,904,035
Restricted unit grants, net	247,822	140,055
Conversion of Limited Partner OP Units to EQR Common Shares	(99,737)	(294,400)
Total Units Outstanding	13,879,400	13,749,690
Units Ownership Interest in Operating Partnership	3.60%	3.60%