Derivative and Other Fair Value Instruments (Details) (Forward Starting Swaps [Member], USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2013
Forward Starting Swaps [Member]
Derivative [Line Items]
Current Notional Balance	$ 400,000
Lowest Possible Notional	400,000
Highest Possible Notional	$ 400,000
Lowest Interest Rate	2.125%
Highest Interest Rate	3.23%
Earliest Maturity Date	2024
Latest Maturity Date	2024

The earliest maturity date on derivatives designated as fair value or cash flow hedging instruments.

No definition available.

Name:	eqr_EarliestMaturityDate
Namespace Prefix:	eqr_
Data Type:	us-types:dateStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Highest interest rate on derivatives designated as fair value or cash flow hedging instruments.

+ References

No definition available.

+ Details

Name:	eqr_HighestInterestRate
Namespace Prefix:	eqr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Highest possible notional amount of all derivatives designated as fair value or cash flow hedging instruments. The notional amount relates to a number of currency units, shares, bushels, pounds or other units specified in a derivative instrument.

+ References

No definition available.

+ Details

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

- Definition

The latest maturity date on derivatives designated as fair value or cash flow hedging instruments.

+ References

No definition available.

+ Details

Name:	eqr_LatestMaturityDate
Namespace Prefix:	eqr_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Lowest interest rate on derivatives designated as fair value or cash flow hedging instruments.

+ References

No definition available.

+ Details

Name:	eqr_LowestInterestRate
Namespace Prefix:	eqr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Lowest possible notional amount of all derivatives designated as fair value or cash flow hedging instruments. The notional amount relates to a number of currency units, shares, bushels, pounds or other units specified in a derivative instrument.

+ References

No definition available.

+ Details

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

- Definition

Aggregate notional amount of all derivatives designated as fair value or cash flow hedging instruments. The notional amount relates to a number of currency units, shares, bushels, pounds, or other units specified in a derivative instrument.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration