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, 2021	Sep. 30, 2020
General and Limited Partner Units
Exercise of share options	1,401,755	219,922
Employee Share Purchase Plan (ESPP)	59,297	69,986
Restricted share grants, net	85,573	178,720
Restricted unit grants, net	155,638	247,822
Common Shares And Units Outstanding	387,862,336	386,118,649
Limited Partner Units
Total Units Outstanding	13,858,073	13,731,315
Restricted unit grants, net	155,638	247,822
Conversion of Limited Partner OP Units to EQR Common Shares	(1,153,963)	(99,737)
Total Units Outstanding	12,859,748	13,879,400
Units Ownership Interest in Operating Partnership	3.30%	3.60%
ERPOP [Member]
General and Limited Partner Units
Common Shares And Units Outstanding	386,160,073	385,402,199
Exercise of share options	1,401,755	219,922
Employee Share Purchase Plan (ESPP)	59,297	69,986
Restricted share grants, net	85,573	178,720
Restricted unit grants, net	155,638	247,822
Common Shares And Units Outstanding	387,862,336	386,118,649
Limited Partner Units
Total Units Outstanding	13,858,073	13,731,315
Restricted unit grants, net	155,638	247,822
Conversion of Limited Partner OP Units to EQR Common Shares	(1,153,963)	(99,737)
Total Units Outstanding	12,859,748	13,879,400
Units Ownership Interest in Operating Partnership	3.30%	3.60%