Commitments to Acquire/Dispose of Real Estate (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014
Purchase Price For Commitments To Acquire	$ 162,350
Rental Properties Disposed of [Member]
Properties Contracted To Be Disposed	1
Sales Price For Commitments To Dispose	169,800
Units Contracted To Be Disposed	150
Retail Site [Member]
Properties Contracted To Be Disposed	1
Sales Price For Commitments To Dispose	123,300
Square footage [Member]
Properties Contracted To Be Disposed	193,230
Rental Properties to be acquired [Member]
Properties Contracted To Be Acquired	1
Units Contracted To Be Acquired	202
Purchase Price For Commitments To Acquire	131,250
Land Parcel [Member]
Purchase Price For Commitments To Acquire	$ 31,100
Land Parcels Contracted To Be Acquired	4

- Definition

Total number of land parcels 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_LandParcelsContractedToBeAcquired
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:	eqr_CommitmentsToAcquireAxis=eqr_LandParcelMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	eqr_CommitmentsToDisposeOfAxis=eqr_RentalPropertiesDisposedOfMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	eqr_CommitmentsToDisposeOfAxis=eqr_SquarefootageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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