Commitments to Acquire/Dispose of Real Estate (Details) - Commitments [Member] $ in Thousands	Feb. 19, 2016 USD ($) property
Properties Contracted To Be Acquired	3
Units Contracted To Be Acquired	549
Purchase Price For Commitments To Acquire	$ 242,880
Properties Contracted To Be Disposed \| property	0
Units Contracted To Be Disposed	0
Sales Price For Commitments To Dispose	$ 14,886
Land [Member]
Sales Price For Commitments To Dispose	$ 14,886
Land Parcels Contracted To Be Disposed	2
Rental Properties to be acquired [Member]
Properties Contracted To Be Acquired	3
Units Contracted To Be Acquired	549
Purchase Price For Commitments To Acquire	$ 242,880

- Definition

Total number of land parcels to be disposed subsequent to the balance sheet date per separate agreements entered into prior to the balance sheet date.

+ References

No definition available.

+ Details

Name:	eqr_LandParcelsContractedToBeDisposed
Namespace Prefix:	eqr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Total number of rental properties to be acquired subsequent to the balance sheet date per separate agreements entered into prior to the balance sheet date.

+ References

No definition available.

+ Details

Name:	eqr_PropertiesContractedToBeAcquired
Namespace Prefix:	eqr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Total number of rental properties to be disposed of subsequent to the balance sheet date per separate agreements entered into prior to the balance sheet date.

+ References

No definition available.

+ Details

Name:	eqr_PropertiesContractedToBeDisposed
Namespace Prefix:	eqr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of the fixed and determinable portion of an unrecorded purchase commitment for the acquisition of a rental property or land parcel subsequent to the balance sheet date.

+ References

No definition available.

+ Details

Name:	eqr_PurchasePriceForCommitmentsToAcquire
Namespace Prefix:	eqr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of the fixed and determinable portion of an unrecorded sales commitment for the disposition of a rental property, land parcel or other property subsequent to the balance sheet date.

+ References

No definition available.

+ Details

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

- Definition

Total number of rental units to be acquired subsequent to the balance sheet date per separate agreements entered into prior to the balance sheet date.

+ References

No definition available.

+ Details

Name:	eqr_UnitsContractedToBeAcquired
Namespace Prefix:	eqr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Total number of rental units to be disposed of subsequent to the balance sheet date per separate agreements entered into prior to the balance sheet date.

+ References

No definition available.

+ Details

Name:	eqr_UnitsContractedToBeDisposed
Namespace Prefix:	eqr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_CommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	eqr_CommitmentsToDisposeOfAxis=us-gaap_LandMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	eqr_CommitmentsToAcquireAxis=eqr_RentalPropertiesToBeAcquiredMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: