Equity, Capital and Other Interests - Changes in Operating Partnership's Issued and Outstanding General Partner Units and Limited Partner Units (Details) - shares	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
General and Limited Partner Units
Exercise of share options	833,669	217,935
Employee Share Purchase Plan (ESPP)	47,761	44,110
Restricted share grants, net	87,377	178,720
Restricted unit grants, net	155,638	245,999
Common Shares And Units Outstanding	387,284,518	386,088,963
Limited Partner Units
Total Units Outstanding	13,858,073	13,731,315
Restricted unit grants, net	155,638	245,999
Conversion of Limited Partner OP Units to EQR Common Shares	(1,084,023)	(97,363)
Total Units Outstanding	12,929,688	13,879,951
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	833,669	217,935
Employee Share Purchase Plan (ESPP)	47,761	44,110
Restricted share grants, net	87,377	178,720
Restricted unit grants, net	155,638	245,999
Common Shares And Units Outstanding	387,284,518	386,088,963
Limited Partner Units
Total Units Outstanding	13,858,073	13,731,315
Restricted unit grants, net	155,638	245,999
Conversion of Limited Partner OP Units to EQR Common Shares	(1,084,023)	(97,363)
Total Units Outstanding	12,929,688	13,879,951
Units Ownership Interest in Operating Partnership	3.30%	3.60%