Share Incentive Plans - Information Regarding Options Outstanding and Exercisable (Parenthetical) (Details)	Dec. 31, 2018 $ / shares
Share Based Compensation [Abstract]
Market value of common shares	$ 66.01

Represents the closing share price of the company's stock on the balance sheet date.

No definition available.

Name:	eqr_MarketValueOfCommonShares
Namespace Prefix:	eqr_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant