Equity, Capital and Other Interests - Changes in Operating Partnership's Issued and Outstanding General Partner Units and Limited Partner Units (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
General and Limited Partner Units
Common Shares And Units Outstanding	383,309,196	381,786,520
Exercise of share options	1,745,050	1,056,388	846,137
Employee Share Purchase Plan (ESPP)	48,131	75,414	68,286
Restricted share grants, net	158,602	123,800	83,451
Restricted unit grants, net	141,220	267,074	291,647
Common Shares And Units Outstanding	385,402,199	383,309,196	381,786,520
Limited Partner Units
Total Units Outstanding	13,904,035	13,768,438	14,626,075
Restricted unit grants, net	141,220	267,074	291,647
Conversion of Limited Partner OP Units to EQR Common Shares	(313,940)	(131,477)	(1,149,284)
Total Units Outstanding	13,731,315	13,904,035	13,768,438
Units Ownership Interest in Operating Partnership	3.60%	3.60%	3.60%
ERPOP [Member]
General and Limited Partner Units
Common Shares And Units Outstanding	383,309,196	381,786,520	380,496,999
Exercise of share options	1,745,050	1,056,388	846,137
Employee Share Purchase Plan (ESPP)	48,131	75,414	68,286
Restricted share grants, net	158,602	123,800	83,451
Restricted unit grants, net	141,220	267,074	291,647
Common Shares And Units Outstanding	385,402,199	383,309,196	381,786,520
Limited Partner Units
Total Units Outstanding	13,904,035	13,768,438	14,626,075
Restricted unit grants, net	141,220	267,074	291,647
Conversion of Limited Partner OP Units to EQR Common Shares	(313,940)	(131,477)	(1,149,284)
Total Units Outstanding	13,731,315	13,904,035	13,768,438
Units Ownership Interest in Operating Partnership	3.60%	3.60%	3.60%