Equity, Capital and Other Interests - Changes in Operating Partnership's Issued and Outstanding Units (Details)	9 Months Ended
	Sep. 30, 2017 shares
General and Limited Partner Units
Exercise of share options	343,527
Employee Share Purchase Plan (ESPP)	54,843
Restricted share grants, net	85,451
Restricted unit grants, net	291,647
Common Shares And Units Outstanding	381,272,467
LIMITED PARTNERS
Total Units Outstanding	14,626,075
Restricted unit grants, net	291,647
Conversion of Limited Partner OP Units to EQR Common Shares	(1,107,735)
Total Units Outstanding	13,809,987
Units Ownership Interest in Operating Partnership	3.60%
ERPOP [Member]
General and Limited Partner Units
Common Shares And Units Outstanding	380,496,999
Exercise of share options	343,527
Employee Share Purchase Plan (ESPP)	54,843
Restricted share grants, net	85,451
Restricted unit grants, net	291,647
Common Shares And Units Outstanding	381,272,467
LIMITED PARTNERS
Total Units Outstanding	14,626,075
Restricted unit grants, net	291,647
Conversion of Limited Partner OP Units to EQR Common Shares	(1,107,735)
Total Units Outstanding	13,809,987
Units Ownership Interest in Operating Partnership	3.60%