Summary of Significant Accounting Policies Tax (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred Tax Assets Gross	$ 46,700,000us-gaap_DeferredTaxAssetsGross
Income and other tax (expense) benefit	1,394,000us-gaap_IncomeTaxExpenseBenefit	1,169,000us-gaap_IncomeTaxExpenseBenefit	514,000us-gaap_IncomeTaxExpenseBenefit
Discontinued Operation, Tax Effect of Discontinued Operation	8,000	449,000	34,000
Provision for income, franchise and excise taxes	1,402,000	1,618,000	548,000
Operating Loss Carryforwards	35,100,000us-gaap_OperatingLossCarryforwards
Tax Treatment Of Dividends And Distributions Ordinary Dividends	$ 1.475	$ 0.662	$ 1.375
Tax Treatment Of Dividends And Distributions Qualified Dividends	$ 0.088	$ 0.050	$ 0.000
Tax Treatment Of Dividends And Distributions Long Term Capital Gain	$ 0.280	$ 0.870	$ 0.253
Tax Treatment Of Dividends And Distributions Unrecaptured Section Twelve Hundred And Fifty Gain	$ 0.157	$ 0.268	$ 0.152
Distributions declared per Common Share outstanding	$ 2.000	$ 1.850	$ 1.780
Land And Depreciable Property Net	$ 16,700,000,000eqr_LandAndDepreciablePropertyNet	$ 15,200,000,000eqr_LandAndDepreciablePropertyNet
Minimum [Member]
Operating Loss Carryforwards, Expiration Dates	Jan. 01, 2029
Maximum [Member]
Operating Loss Carryforwards, Expiration Dates	Dec. 31, 2032

Carrying value of land and property after the effect of depreciation for Federal Income Tax purposes.

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- Definition

The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations and discontinued operations.

+ References

No definition available.

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The cash outflow for gains from qualifying investments owned for longer than 12 months and then sold for prices greater than the purchase prices. Taxes can be deferred until the sale of assets.

+ References

No definition available.

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The cash outflow per share from distributions of an entity's earnings to common stockholders. Ordinary dividends are paid out of the earnings and profits of the entity and are taxed as ordinary income.

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Tax Treatment Of Dividends And Distributions Qualified Dividends

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- Definition

The cash outflow related to a type of depreciation-recapture income that is realized on the sale of depreciable real estate. Unrecaptured Section 1250 income is taxed at a 25% maximum capital gains rate (or in some cases less).

+ References

No definition available.

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- Definition

Aggregate dividends declared during the period for each share of common stock outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

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-Topic 505

-SubTopic 10

-Section S99

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-Subparagraph (SX 210.3-04)

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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-Glossary Deferred Tax Asset

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Tax effect allocated to a disposal group that is classified as a component of the entity reported as a separate component of income before extraordinary items. Includes the tax effects of the following: income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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-Publisher FASB

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- Definition

Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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Expiration date of each operating loss carryforward included in operating loss carryforward, in CCYY-MM-DD format.

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