Equity, Capital and Other Interests - Changes in Redemption Value of Redeemable Limited Partners Interest (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Equity Capital And Other Interests [Abstract]
Redeemable Limited Partners	$ 463,400	$ 379,106	$ 366,955
Limited Partners Change In Redemption Value	(125,224)	82,283	13,922
Limited Partners Change In Carrying Value	775	2,011	(1,771)
Redeemable Limited Partners	$ 338,951	$ 463,400	$ 379,106

The greater of carrying value (book value) or fair market value of an entity's issued and outstanding Units which is not included within Partner's Capital in Capital. Represents a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the units to another class of equity.

No definition available.

Name:	eqr_RedeemableLimitedPartners
Namespace Prefix:	eqr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant