Equity, Capital and Other Interests - Changes in Operating Partnership's Issued and Outstanding Units (Details)	6 Months Ended
	Jun. 30, 2018 shares
General and Limited Partner Units
Exercise of share options	80,875
Employee Share Purchase Plan (ESPP)	44,858
Restricted share grants, net	123,027
Restricted unit grants, net	267,074
Common Shares And Units Outstanding	382,302,354
LIMITED PARTNERS
Total Units Outstanding	13,768,438
Restricted unit grants, net	267,074
Conversion of Limited Partner OP Units to EQR Common Shares	(11,494)
Total Units Outstanding	14,024,018
Units Ownership Interest in Operating Partnership	3.70%
ERPOP [Member]
General and Limited Partner Units
Common Shares And Units Outstanding	381,786,520
Exercise of share options	80,875
Employee Share Purchase Plan (ESPP)	44,858
Restricted share grants, net	123,027
Restricted unit grants, net	267,074
Common Shares And Units Outstanding	382,302,354
LIMITED PARTNERS
Total Units Outstanding	13,768,438
Restricted unit grants, net	267,074
Conversion of Limited Partner OP Units to EQR Common Shares	(11,494)
Total Units Outstanding	14,024,018
Units Ownership Interest in Operating Partnership	3.70%