Equity, Capital and Other Interests - Changes in Operating Partnership's Issued and Outstanding Units (Details)	9 Months Ended
	Sep. 30, 2018 shares
General and Limited Partner Units
Exercise of share options	194,796
Employee Share Purchase Plan (ESPP)	61,321
Restricted share grants, net	122,877
Restricted unit grants, net	267,074
Common Shares And Units Outstanding	382,432,588
LIMITED PARTNERS
Total Units Outstanding	13,768,438
Restricted unit grants, net	267,074
Conversion of Limited Partner OP Units to EQR Common Shares	(12,510)
Total Units Outstanding	14,023,002
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	194,796
Employee Share Purchase Plan (ESPP)	61,321
Restricted share grants, net	122,877
Restricted unit grants, net	267,074
Common Shares And Units Outstanding	382,432,588
LIMITED PARTNERS
Total Units Outstanding	13,768,438
Restricted unit grants, net	267,074
Conversion of Limited Partner OP Units to EQR Common Shares	(12,510)
Total Units Outstanding	14,023,002
Units Ownership Interest in Operating Partnership	3.70%