$EQR
EQUITY RESIDENTIAL Stock $eqr

$eqr Overview Financials Valuation SEC Filings Company Website

2010 Q4 Form 8-K Financial Statement

#000090610712000019 Filed on June 13, 2012

Income Statement

Concept	2010 Q4	2010 Q3	2010 Q2
Revenue	$456.0M	$446.9M	$434.5M
YoY Change	-1.16%	3.05%	-9.31%
Cost Of Revenue	$131.5M	$180.2M	$169.7M
YoY Change	-28.22%	-0.39%	-9.88%
Gross Profit	$224.2M	$273.8M	$266.1M
YoY Change	-19.38%	8.31%	-8.49%
Gross Profit Margin	49.17%	61.26%	61.24%
Selling, General & Admin	$8.900M	$10.20M	$10.10M
YoY Change	4.71%	3.03%	-0.98%
% of Gross Profit	3.97%	3.73%	3.8%
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$171.7M	$174.0M	$175.0M
YoY Change	15.31%	16.23%	15.66%
% of Gross Profit	76.58%	63.55%	65.76%
Operating Expenses	$132.5M	$168.5M	$169.4M
YoY Change	-12.31%	18.75%	10.57%
Operating Profit	$74.58M	$102.6M	$95.64M
YoY Change	-41.28%	-7.46%	-30.49%
Interest Expense	-$114.2M	-$123.4M	-$113.1M
YoY Change	-20.31%	1.82%	0.98%
% of Operating Profit	-153.13%	-120.24%	-118.25%
Other Income/Expense, Net	-$2.300M	-$3.500M	-$1.600M
YoY Change
Pretax Income	-$42.30M	-$22.70M	-$17.90M
YoY Change	105.34%	198.68%	-223.45%
Income Tax	$0.00	$300.0K	-$100.0K
% Of Pretax Income
Net Earnings	$198.2M	$29.83M	$10.09M
YoY Change	337.55%	-78.07%	-89.93%
Net Earnings / Revenue	43.47%	6.67%	2.32%
Basic Earnings Per Share	$0.65	$0.09	$0.02
Diluted Earnings Per Share	$0.65	$0.09	$0.02
COMMON SHARES
Basic Shares Outstanding	285.9M shares	282.7M shares	282.2M shares
Diluted Shares Outstanding	285.9M shares	282.7M shares	282.2M shares

Balance Sheet

Concept	2010 Q4	2010 Q3	2010 Q2
SHORT-TERM ASSETS
Cash & Short-Term Investments	$431.0M	$44.00M	$48.00M
YoY Change	123.32%	-93.1%	-92.8%
Cash & Equivalents	$431.4M	$44.00M	$48.00M
Short-Term Investments
Other Short-Term Assets
YoY Change
Inventory
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets	$431.0M	$44.00M	$48.00M
YoY Change	123.32%	-93.1%	-92.8%
LONG-TERM ASSETS
Property, Plant & Equipment	$15.37B	$15.73B	$15.27B
YoY Change	5.33%	7.8%	2.68%
Goodwill
YoY Change
Intangibles
YoY Change
Long-Term Investments	$3.000M	$0.00	$3.000M
YoY Change	-57.14%	-100.0%	-25.0%
Other Assets	$236.0M	$174.0M	$169.0M
YoY Change	-43.27%	-59.44%	-26.52%
Total Long-Term Assets	$15.75B	$16.04B	$15.58B
YoY Change	3.47%	5.87%	2.1%
TOTAL ASSETS
Total Short-Term Assets	$431.0M	$44.00M	$48.00M
Total Long-Term Assets	$15.75B	$16.04B	$15.58B
Total Assets	$16.18B	$16.09B	$15.63B
YoY Change	4.97%	1.87%	-1.87%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$39.00M	$111.0M	$82.00M
YoY Change	-33.9%	-15.91%	-28.07%
Accrued Expenses	$99.00M	$71.00M	$97.00M
YoY Change	-2.94%	-2.74%	-10.19%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$340.0M	$347.0M	$344.0M
YoY Change	5.92%	-5.19%	-19.25%
LONG-TERM LIABILITIES
Long-Term Debt	$9.948B	$10.18B	$9.659B
YoY Change	5.91%	3.48%	-3.16%
Other Long-Term Liabilities	$304.0M	$341.0M	$312.0M
YoY Change	11.76%	29.17%	20.46%
Total Long-Term Liabilities	$10.25B	$10.52B	$9.971B
YoY Change	6.07%	4.15%	-2.56%
TOTAL LIABILITIES
Total Short-Term Liabilities	$340.0M	$347.0M	$344.0M
Total Long-Term Liabilities	$10.25B	$10.52B	$9.971B
Total Liabilities	$10.59B	$11.34B	$10.75B
YoY Change	2.14%	4.67%	-2.24%
SHAREHOLDERS EQUITY
Retained Earnings	$203.6M
YoY Change
Common Stock	$2.902M
YoY Change
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$5.090B	$4.749B	$4.877B
YoY Change
Total Liabilities & Shareholders Equity	$16.18B	$16.09B	$15.63B
YoY Change	4.97%	1.87%	-1.87%

Cashflow Statement

Concept	2010 Q4	2010 Q3	2010 Q2
OPERATING ACTIVITIES
Net Income	$198.2M	$29.83M	$10.09M
YoY Change	337.55%	-78.07%	-89.93%
Depreciation, Depletion And Amortization	$171.7M	$174.0M	$175.0M
YoY Change	15.31%	16.23%	15.66%
Cash From Operating Activities	$165.3M	$204.0M	$201.2M
YoY Change	19.35%	22.38%	-9.82%
INVESTING ACTIVITIES
Capital Expenditures	-$155.4M	-$495.0M	-$255.6M
YoY Change	-38.09%	300.81%	72.59%
Acquisitions
YoY Change
Other Investing Activities	$428.6M	$69.10M	$47.10M
YoY Change	239.35%	-63.54%	-87.68%
Cash From Investing Activities	$273.0M	-$425.9M	-$208.4M
YoY Change	-318.93%	-745.3%	-188.95%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-50.70M	217.6M	-5.000M
YoY Change	-88.93%	-182.86%	-97.71%
NET CHANGE
Cash From Operating Activities	165.3M	204.0M	201.2M
Cash From Investing Activities	273.0M	-425.9M	-208.4M
Cash From Financing Activities	-50.70M	217.6M	-5.000M
Net Change In Cash	387.6M	-4.300M	-12.20M
YoY Change	-187.24%	-85.62%	-105.11%
FREE CASH FLOW
Cash From Operating Activities	$165.3M	$204.0M	$201.2M
Capital Expenditures	-$155.4M	-$495.0M	-$255.6M
Free Cash Flow	$320.7M	$699.0M	$456.8M
YoY Change	-17.66%	140.87%	23.06%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2009	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	1661000	USD
CY2010	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	0	USD
CY2011	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	0	USD
CY2011Q4	us-gaap	Accumulated Amortization Deferred Finance Costs AccumulatedAmortizationDeferredFinanceCosts	37672777	USD
CY2010Q4	us-gaap	Accumulated Amortization Deferred Finance Costs AccumulatedAmortizationDeferredFinanceCosts	43900000	USD
CY2010Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-57818000	USD
CY2011Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-196718000	USD
CY2010Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	4741521000	USD
CY2011Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	5047186000	USD
CY2009	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	19804000	USD
CY2010	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	21016000	USD
CY2011	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	23482000	USD
CY2009	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	17843000	USD
CY2010	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	18875000	USD
CY2011	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	21177000	USD
CY2009	us-gaap	Amortization Of Debt Discount Premium AmortizationOfDebtDiscountPremium	5857000	USD
CY2010	us-gaap	Amortization Of Debt Discount Premium AmortizationOfDebtDiscountPremium	-471000	USD
CY2011	us-gaap	Amortization Of Debt Discount Premium AmortizationOfDebtDiscountPremium	-1478000	USD
CY2009	us-gaap	Amortization Of Deferred Hedge Gains AmortizationOfDeferredHedgeGains	2228000	USD
CY2011	us-gaap	Amortization Of Deferred Hedge Gains AmortizationOfDeferredHedgeGains	3808000	USD
CY2010	us-gaap	Amortization Of Deferred Hedge Gains AmortizationOfDeferredHedgeGains	2804000	USD
CY2010	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	10114000	USD
CY2011	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	17006000	USD
CY2009	us-gaap	Amortization Of Financing Costs AmortizationOfFinancingCosts	12327000	USD
CY2010	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	325103	shares
CY2011	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	0	shares
CY2009	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	402501	shares
CY2009	us-gaap	Asset Impairment Charges AssetImpairmentCharges	11124000	USD
CY2011	us-gaap	Asset Impairment Charges AssetImpairmentCharges	0	USD
CY2010	us-gaap	Asset Impairment Charges AssetImpairmentCharges	45380000	USD
CY2010Q4	us-gaap	Assets Assets	16184194000	USD
CY2011Q4	us-gaap	Assets Assets	16659303000	USD
CY2010Q4	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	75123000	USD
CY2011Q4	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	81948000	USD
CY2010Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	290197242	shares
CY2009Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	279959048	shares
CY2011Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	297508185	shares
CY2008Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	272786760	shares
CY2011Q4	us-gaap	Common Stock Value CommonStockValue	2975000	USD
CY2010Q4	us-gaap	Assets Fair Value Disclosure Nonrecurring AssetsFairValueDisclosureNonrecurring	56000000	USD
CY2010Q4	us-gaap	Available For Sale Securities Amortized Cost AvailableForSaleSecuritiesAmortizedCost	675000	USD
CY2011Q4	us-gaap	Available For Sale Securities Amortized Cost AvailableForSaleSecuritiesAmortizedCost	675000	USD
CY2010Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	1194000	USD
CY2011Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	1550000	USD
CY2010Q4	us-gaap	Available For Sale Securities Gross Unrealized Losses1 AvailableForSaleSecuritiesGrossUnrealizedLosses1	0	USD
CY2011Q4	us-gaap	Available For Sale Securities Gross Unrealized Losses1 AvailableForSaleSecuritiesGrossUnrealizedLosses1	0	USD
CY2010Q4	us-gaap	Availableforsale Securities Gross Unrealized Gain AvailableforsaleSecuritiesGrossUnrealizedGain	519000	USD
CY2011Q4	us-gaap	Availableforsale Securities Gross Unrealized Gain AvailableforsaleSecuritiesGrossUnrealizedGain	875000	USD
CY2009Q4	us-gaap	Business Acquisition Cost Of Acquired Entity Purchase Price BusinessAcquisitionCostOfAcquiredEntityPurchasePrice	9200000	USD
CY2010Q4	us-gaap	Business Acquisition Cost Of Acquired Entity Purchase Price BusinessAcquisitionCostOfAcquiredEntityPurchasePrice	1554570000	USD
CY2011Q4	us-gaap	Business Acquisition Cost Of Acquired Entity Purchase Price BusinessAcquisitionCostOfAcquiredEntityPurchasePrice	1597111000	USD
CY2011Q4	us-gaap	Business Acquisition Cost Of Acquired Entity Transaction Costs BusinessAcquisitionCostOfAcquiredEntityTransactionCosts	400000	USD
CY2010Q4	us-gaap	Business Acquisition Percentage Of Voting Interests Acquired BusinessAcquisitionPercentageOfVotingInterestsAcquired	0.75
CY2010	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	6600000	USD
CY2011	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	9482000	USD
CY2009	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	1650000	USD
CY2010Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	431408000	USD
CY2011Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	383921000	USD
CY2009Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	193288000	USD
CY2008Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	890794000	USD
CY2010	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	238120000	USD
CY2009	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	-697506000	USD
CY2011	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	-47487000	USD
CY2011Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2010Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2010	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.470
CY2009	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.640
CY2011	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.580
CY2011Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.01
CY2010Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.01
CY2010Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	1000000000	shares
CY2011Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	1000000000	shares
CY2011Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	297508185	shares
CY2010Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	290197242	shares
CY2010Q4	us-gaap	Common Stock Value CommonStockValue	2902000	USD
CY2011	us-gaap	Comparability Of Prior Year Financial Data ComparabilityOfPriorYearFinancialData	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:17px;text-align:left;text-indent:24px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-style:italic;">Reclassifications</font></div><div style="line-height:120%;padding-top:9px;text-align:justify;text-indent:48px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Certain reclassifications considered necessary for a fair presentation have been made to the prior period financial statements in order to conform to the current year presentation. These reclassifications have not changed the results of operations or equity/capital. </font></div></div>
CY2009	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	402753000	USD
CY2011	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	754685000	USD
CY2010	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	221111000	USD
CY2011	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	41612000	USD
CY2010	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	12373000	USD
CY2009	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	19756000	USD
CY2011	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	796297000	USD
CY2009	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	422509000	USD
CY2010	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	233484000	USD
CY2006Q3	us-gaap	Convertible Debt ConvertibleDebt	650000000	USD
CY2011Q3	us-gaap	Convertible Debt ConvertibleDebt	482500000	USD
CY2009	us-gaap	Cost Of Property Repairs And Maintenance CostOfPropertyRepairsAndMaintenance	365448000	USD
CY2011	us-gaap	Cost Of Property Repairs And Maintenance CostOfPropertyRepairsAndMaintenance	412233000	USD
CY2010	us-gaap	Cost Of Property Repairs And Maintenance CostOfPropertyRepairsAndMaintenance	397573000	USD
CY2009	us-gaap	Costs And Expenses CostsAndExpenses	1196297000	USD
CY2011	us-gaap	Costs And Expenses CostsAndExpenses	1404409000	USD
CY2010	us-gaap	Costs And Expenses CostsAndExpenses	1385554000	USD
CY2006Q3	us-gaap	Debt Instrument Convertible Carrying Amount Of The Equity Component DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent	44300000	USD
CY2008Q4	us-gaap	Debt Instrument Convertible Carrying Amount Of The Equity Component DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent	44300000	USD
CY2011Q4	us-gaap	Debt Instrument Convertible Carrying Amount Of The Equity Component DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent	44300000	USD
CY2010Q4	us-gaap	Debt Instrument Convertible Carrying Amount Of The Equity Component DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent	44300000	USD
CY2006Q3	us-gaap	Debt Instrument Convertible Effective Interest Rate DebtInstrumentConvertibleEffectiveInterestRate	0.0580
CY2009	us-gaap	Debt Instrument Convertible Interest Expense DebtInstrumentConvertibleInterestExpense	20600000	USD
CY2011	us-gaap	Debt Instrument Convertible Interest Expense DebtInstrumentConvertibleInterestExpense	11800000	USD
CY2010	us-gaap	Debt Instrument Convertible Interest Expense DebtInstrumentConvertibleInterestExpense	18600000	USD
CY2011Q4	us-gaap	Debt Instrument Face Amount DebtInstrumentFaceAmount	1000000000	USD
CY2010Q4	us-gaap	Debt Instrument Face Amount DebtInstrumentFaceAmount	600000000	USD
CY2009Q4	us-gaap	Debt Instrument Face Amount DebtInstrumentFaceAmount	500000000	USD
CY2011Q4	us-gaap	Debt Instrument Fee Amount DebtInstrumentFeeAmount	2625000	USD
CY2006Q3	us-gaap	Debt Instrument Interest Rate Stated Percentage DebtInstrumentInterestRateStatedPercentage	0.0385
CY2011Q4	us-gaap	Debt Instrument Interest Rate Stated Percentage DebtInstrumentInterestRateStatedPercentage	0.0695
CY2010	us-gaap	Debt Instrument Interest Rate Stated Percentage Rate Range Maximum DebtInstrumentInterestRateStatedPercentageRateRangeMaximum	0.1125
CY2011	us-gaap	Debt Instrument Interest Rate Stated Percentage Rate Range Maximum DebtInstrumentInterestRateStatedPercentageRateRangeMaximum	0.1125
CY2010	us-gaap	Debt Instrument Interest Rate Stated Percentage Rate Range Minimum DebtInstrumentInterestRateStatedPercentageRateRangeMinimum	0.0021
CY2011	us-gaap	Debt Instrument Interest Rate Stated Percentage Rate Range Minimum DebtInstrumentInterestRateStatedPercentageRateRangeMinimum	0.0005
CY2010	us-gaap	Deferred Compensation Arrangement With Individual Compensation Expense DeferredCompensationArrangementWithIndividualCompensationExpense	928941	USD
CY2011	us-gaap	Deferred Compensation Arrangement With Individual Compensation Expense DeferredCompensationArrangementWithIndividualCompensationExpense	1000111	USD
CY2009	us-gaap	Deferred Compensation Arrangement With Individual Compensation Expense DeferredCompensationArrangementWithIndividualCompensationExpense	1183691	USD
CY2011Q4	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	44608000	USD
CY2010Q4	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	42033000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	31700000	USD
CY2011Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments In Year Five DefinedBenefitPlanExpectedFutureBenefitPaymentsInYearFive	1671000	USD
CY2011Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments In Year Four DefinedBenefitPlanExpectedFutureBenefitPaymentsInYearFour	1671000	USD
CY2011Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments In Year One DefinedBenefitPlanExpectedFutureBenefitPaymentsInYearOne	1767000	USD
CY2011Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments In Year Three DefinedBenefitPlanExpectedFutureBenefitPaymentsInYearThree	1672000	USD
CY2011Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments In Year Two DefinedBenefitPlanExpectedFutureBenefitPaymentsInYearTwo	1480000	USD
CY2010	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	4000000	USD
CY2011	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	3700000	USD
CY2009	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	3500000	USD
CY2011	us-gaap	Depreciation Depreciation	642415000	USD
CY2009	us-gaap	Depreciation Depreciation	514200000	USD
CY2010	us-gaap	Depreciation Depreciation	608612000	USD
CY2010Q4	us-gaap	Derivative Assets DerivativeAssets	3276000	USD
CY2010Q4	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	12521000	USD
CY2011Q4	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	8972000	USD
CY2010Q4	us-gaap	Derivative Fair Value Of Derivative Liability DerivativeFairValueOfDerivativeLiability	37756000	USD
CY2011Q4	us-gaap	Derivative Fair Value Of Derivative Liability DerivativeFairValueOfDerivativeLiability	32278000	USD
CY2009	us-gaap	Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet	0	USD
CY2011	us-gaap	Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet	-170000	USD
CY2010	us-gaap	Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet	0	USD
CY2009	us-gaap	Derivative Instruments Gain Recognized In Other Comprehensive Income Effective Portion DerivativeInstrumentsGainRecognizedInOtherComprehensiveIncomeEffectivePortion	37676000	USD
CY2011	us-gaap	Derivative Instruments Gain Recognized In Other Comprehensive Income Effective Portion DerivativeInstrumentsGainRecognizedInOtherComprehensiveIncomeEffectivePortion	-143768000	USD
CY2010	us-gaap	Derivative Instruments Gain Recognized In Other Comprehensive Income Effective Portion DerivativeInstrumentsGainRecognizedInOtherComprehensiveIncomeEffectivePortion	-65894000	USD
CY2009	us-gaap	Derivative Instruments Loss Reclassified From Accumulated Oci Into Income Effective Portion DerivativeInstrumentsLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortion	-3724000	USD
CY2011	us-gaap	Derivative Instruments Loss Reclassified From Accumulated Oci Into Income Effective Portion DerivativeInstrumentsLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortion	-4343000	USD
CY2010	us-gaap	Derivative Instruments Loss Reclassified From Accumulated Oci Into Income Effective Portion DerivativeInstrumentsLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortion	-3338000	USD
CY2010Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	1322000	USD
CY2011Q4	us-gaap	Development In Process DevelopmentInProcess	160190000	USD
CY2010Q4	us-gaap	Development In Process DevelopmentInProcess	130337000	USD
CY2011	us-gaap	Discontinued Operation Gain Loss On Disposal Of Discontinued Operation Net Of Tax DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax	826489000	USD
CY2009	us-gaap	Discontinued Operation Gain Loss On Disposal Of Discontinued Operation Net Of Tax DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax	335299000	USD
CY2010	us-gaap	Discontinued Operation Gain Loss On Disposal Of Discontinued Operation Net Of Tax DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax	297956000	USD
CY2010	us-gaap	Discontinued Operation Tax Effect Of Discontinued Operation DiscontinuedOperationTaxEffectOfDiscontinuedOperation	86000	USD
CY2011	us-gaap	Discontinued Operation Tax Effect Of Discontinued Operation DiscontinuedOperationTaxEffectOfDiscontinuedOperation	-243000	USD
CY2009	us-gaap	Discontinued Operation Tax Effect Of Discontinued Operation DiscontinuedOperationTaxEffectOfDiscontinuedOperation	-1073000	USD
CY2009	us-gaap	Disposal Group Including Discontinued Operation Interest Expense DisposalGroupIncludingDiscontinuedOperationInterestExpense	14262000	USD
CY2011	us-gaap	Disposal Group Including Discontinued Operation Interest Expense DisposalGroupIncludingDiscontinuedOperationInterestExpense	1120000	USD
CY2010	us-gaap	Disposal Group Including Discontinued Operation Interest Expense DisposalGroupIncludingDiscontinuedOperationInterestExpense	12584000	USD
CY2011	us-gaap	Disposal Group Including Discontinued Operation Operating Expense DisposalGroupIncludingDiscontinuedOperationOperatingExpense	82552000	USD
CY2009	us-gaap	Disposal Group Including Discontinued Operation Operating Expense DisposalGroupIncludingDiscontinuedOperationOperatingExpense	271896000	USD
CY2010	us-gaap	Disposal Group Including Discontinued Operation Operating Expense DisposalGroupIncludingDiscontinuedOperationOperatingExpense	210457000	USD
CY2011	us-gaap	Disposal Group Including Discontinued Operation Operating Income Loss DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss	33798000	USD
CY2009	us-gaap	Disposal Group Including Discontinued Operation Operating Income Loss DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss	123823000	USD
CY2010	us-gaap	Disposal Group Including Discontinued Operation Operating Income Loss DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss	98488000	USD
CY2011Q4	us-gaap	Disposal Group Including Discontinued Operation Property Plant And Equipment Net DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNet	71606152.55	USD
CY2010Q4	us-gaap	Disposal Group Including Discontinued Operation Property Plant And Equipment Net DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNet	732041347.88	USD
CY2010	us-gaap	Disposal Group Including Discontinued Operation Revenue DisposalGroupIncludingDiscontinuedOperationRevenue	308945000	USD
CY2011	us-gaap	Disposal Group Including Discontinued Operation Revenue DisposalGroupIncludingDiscontinuedOperationRevenue	116350000	USD
CY2009	us-gaap	Disposal Group Including Discontinued Operation Revenue DisposalGroupIncludingDiscontinuedOperationRevenue	395719000	USD
CY2010	us-gaap	Distributions Per Limited Partnership And General Partnership Unit Outstanding Basic DistributionsPerLimitedPartnershipAndGeneralPartnershipUnitOutstandingBasic	1.470
CY2011	us-gaap	Distributions Per Limited Partnership And General Partnership Unit Outstanding Basic DistributionsPerLimitedPartnershipAndGeneralPartnershipUnitOutstandingBasic	1.580
CY2009	us-gaap	Distributions Per Limited Partnership And General Partnership Unit Outstanding Basic DistributionsPerLimitedPartnershipAndGeneralPartnershipUnitOutstandingBasic	1.640
CY2011Q4	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	179079000	USD
CY2010Q4	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	140905000	USD
CY2010	us-gaap	Dividends Preferred Stock DividendsPreferredStock	14368000	USD
CY2009	us-gaap	Dividends Preferred Stock DividendsPreferredStock	14479000	USD
CY2011	us-gaap	Dividends Preferred Stock DividendsPreferredStock	13865000	USD
CY2010	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.952
CY2009	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.271
CY2011	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.984
CY2010Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.09
CY2010Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.18
CY2010Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.65
CY2010Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.02
CY2011Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.35
CY2011Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.42
CY2011Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.33
CY2011Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.88
CY2011	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.950
CY2009	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.271
CY2010	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.952
CY2010Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.09
CY2010Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.02
CY2010Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.65
CY2010Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.18
CY2011Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.42
CY2011Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.85
CY2011Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.33
CY2011Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.35
CY2009	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	1961000	USD
CY2010	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	2141000	USD
CY2011	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	2305000	USD
CY2011Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	22800000	USD
CY2011	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition	1.67
CY2009	us-gaap	Equity Method Investment Dividends Or Distributions EquityMethodInvestmentDividendsOrDistributions	153000	USD
CY2011	us-gaap	Equity Method Investment Dividends Or Distributions EquityMethodInvestmentDividendsOrDistributions	319000	USD
CY2010	us-gaap	Equity Method Investment Dividends Or Distributions EquityMethodInvestmentDividendsOrDistributions	61000	USD
CY2010Q4	us-gaap	Equity Method Investment Ownership Percentage EquityMethodInvestmentOwnershipPercentage	0.25
CY2011Q4	us-gaap	Equity Method Investment Ownership Percentage EquityMethodInvestmentOwnershipPercentage	0.20
CY2011	us-gaap	Equity Method Investment Realized Gain Loss On Disposal EquityMethodInvestmentRealizedGainLossOnDisposal	0	USD
CY2010	us-gaap	Equity Method Investment Realized Gain Loss On Disposal EquityMethodInvestmentRealizedGainLossOnDisposal	28101000	USD
CY2009	us-gaap	Equity Method Investment Realized Gain Loss On Disposal EquityMethodInvestmentRealizedGainLossOnDisposal	10689000	USD
CY2010Q4	us-gaap	Fixtures And Equipment Gross FixturesAndEquipmentGross	1231391000	USD
CY2011Q4	us-gaap	Fixtures And Equipment Gross FixturesAndEquipmentGross	1292124000	USD
CY2009	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-17525000	USD
CY2010	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-2457000	USD
CY2011	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
CY2010	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	39881000	USD
CY2011	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	43606000	USD
CY2009	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	38985000	USD
CY2010	us-gaap	Impairment Of Real Estate ImpairmentOfRealEstate	-45380000	USD
CY2011	us-gaap	Income Loss Attributable To Noncontrolling Interest IncomeLossAttributableToNoncontrollingInterest	2738000	USD
CY2010	us-gaap	Income Loss Attributable To Noncontrolling Interest IncomeLossAttributableToNoncontrollingInterest	-4732000	USD
CY2009	us-gaap	Income Loss Attributable To Noncontrolling Interest IncomeLossAttributableToNoncontrollingInterest	-4273000	USD
CY2011	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	59008000	USD
CY2009	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	-72877000	USD
CY2010	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	-97209000	USD
CY2011	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	72954000	USD
CY2010	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	-113978000	USD
CY2009	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	-68378000	USD
CY2011	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	76443000	USD
CY2009	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	-63220000	USD
CY2010	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	-88299000	USD
CY2010Q4	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	-49721000	USD
CY2010Q2	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	-13921000	USD
CY2010Q3	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	-2276000	USD
CY2010Q1	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	-22381000	USD
CY2011Q1	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	-8913000	USD
CY2011Q3	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	32287000	USD
CY2011Q2	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	16298000	USD
CY2011Q4	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	36771000	USD
CY2011	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.200
CY2009	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	-0.266
CY2010	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	-0.344
CY2009	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	-0.266
CY2011	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.198
CY2010	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	-0.344
CY2010	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	384282000	USD
CY2009	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	445249000	USD
CY2011	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	858754000	USD
CY2010Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	24010000	USD
CY2010Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	80237000	USD
CY2010Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	247933000	USD
CY2010Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	32102000	USD
CY2011Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	141979000	USD
CY2011Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	80690000	USD
CY2011Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	565455000	USD
CY2011Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	70630000	USD
CY2009	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	420671000	USD
CY2011	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	820712000	USD
CY2010	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	366451000	USD
CY2009	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	1.537
CY2011	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	2.784
CY2010	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	1.296
CY2010	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	1.296
CY2011	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	2.752
CY2009	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	1.537
CY2009	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	-2815000	USD
CY2010	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	-735000	USD
CY2011	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	0	USD
CY2011	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	728000	USD
CY2010	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	292000	USD
CY2009	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	2716000	USD
CY2010	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-2740000	USD
CY2011	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	645000	USD
CY2009	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	3968000	USD
CY2011	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	332000	USD
CY2009	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	-34524000	USD
CY2010	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	-5454000	USD
CY2011	us-gaap	Increase Decrease In Fair Value Of Hedged Item In Interest Rate Fair Value Hedge IncreaseDecreaseInFairValueOfHedgedItemInInterestRateFairValueHedge	3549000	USD
CY2010	us-gaap	Increase Decrease In Fair Value Of Hedged Item In Interest Rate Fair Value Hedge IncreaseDecreaseInFairValueOfHedgedItemInInterestRateFairValueHedge	-7335000	USD
CY2009	us-gaap	Increase Decrease In Fair Value Of Hedged Item In Interest Rate Fair Value Hedge IncreaseDecreaseInFairValueOfHedgedItemInInterestRateFairValueHedge	1167000	USD
CY2011	us-gaap	Increase Decrease In Fair Value Of Interest Rate Fair Value Hedging Instruments IncreaseDecreaseInFairValueOfInterestRateFairValueHedgingInstruments	-3549000	USD
CY2010	us-gaap	Increase Decrease In Fair Value Of Interest Rate Fair Value Hedging Instruments IncreaseDecreaseInFairValueOfInterestRateFairValueHedgingInstruments	7335000	USD
CY2009	us-gaap	Increase Decrease In Fair Value Of Interest Rate Fair Value Hedging Instruments IncreaseDecreaseInFairValueOfInterestRateFairValueHedgingInstruments	-1167000	USD
CY2010	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-4000000	USD
CY2011	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-10510000	USD
CY2009	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-11997000	USD
CY2009	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-11768000	USD
CY2010	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	9048000	USD
CY2011	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	2743000	USD
CY2011	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-8245000	USD
CY2009	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	2220000	USD
CY2010	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	9972000	USD
CY2009	us-gaap	Increase Decrease In Restricted Cash For Operating Activities IncreaseDecreaseInRestrictedCashForOperatingActivities	-3117000	USD
CY2011	us-gaap	Increase Decrease In Restricted Cash For Operating Activities IncreaseDecreaseInRestrictedCashForOperatingActivities	-4523000	USD
CY2010	us-gaap	Increase Decrease In Restricted Cash For Operating Activities IncreaseDecreaseInRestrictedCashForOperatingActivities	-3316000	USD
CY2010	us-gaap	Increase Decrease In Security Deposits IncreaseDecreaseInSecurityDeposits	1007000	USD
CY2011	us-gaap	Increase Decrease In Security Deposits IncreaseDecreaseInSecurityDeposits	4474000	USD
CY2009	us-gaap	Increase Decrease In Security Deposits IncreaseDecreaseInSecurityDeposits	-5091000	USD
CY2010	us-gaap	Interest And Dividend Income Securities Available For Sale InterestAndDividendIncomeSecuritiesAvailableForSale	61000	USD
CY2011	us-gaap	Interest And Dividend Income Securities Available For Sale InterestAndDividendIncomeSecuritiesAvailableForSale	0	USD
CY2009	us-gaap	Interest And Other Income InterestAndOtherIncome	16578000	USD
CY2011	us-gaap	Interest And Other Income InterestAndOtherIncome	7977000	USD
CY2010	us-gaap	Interest And Other Income InterestAndOtherIncome	5166000	USD
CY2010	us-gaap	Interest Costs Capitalized InterestCostsCapitalized	-13008000	USD
CY2009	us-gaap	Interest Costs Capitalized InterestCostsCapitalized	-34859000	USD
CY2011	us-gaap	Interest Costs Capitalized InterestCostsCapitalized	-9108000	USD
CY2010	us-gaap	Interest Expense Debt InterestExpenseDebt	465792000	USD
CY2009	us-gaap	Interest Expense Debt InterestExpenseDebt	490670000	USD
CY2011	us-gaap	Interest Expense Debt InterestExpenseDebt	468320000	USD
CY2010	us-gaap	Interest Paid Net InterestPaidNet	475374000	USD
CY2009	us-gaap	Interest Paid Net InterestPaidNet	508847000	USD
CY2011	us-gaap	Interest Paid Net InterestPaidNet	477434000	USD
CY2010Q4	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	98631000	USD
CY2011Q4	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	88121000	USD
CY2011Q4	us-gaap	Interest Rate Cash Flow Hedge Gain Loss To Be Reclassified During Next12 Months Net InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet	19500000	USD
CY2010Q4	us-gaap	Investment Building And Building Improvements InvestmentBuildingAndBuildingImprovements	13995121000	USD
CY2011Q4	us-gaap	Investment Building And Building Improvements InvestmentBuildingAndBuildingImprovements	14262616000	USD
CY2011Q4	us-gaap	Investments In Affiliates Subsidiaries Associates And Joint Ventures InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures	12327000	USD
CY2010Q4	us-gaap	Investments In Affiliates Subsidiaries Associates And Joint Ventures InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures	3167000	USD
CY2011Q4	us-gaap	Land Land	4367816000	USD
CY2010Q4	us-gaap	Land Land	4110275000	USD
CY2011Q4	us-gaap	Land Available For Development LandAvailableForDevelopment	325200000	USD
CY2010Q4	us-gaap	Land Available For Development LandAvailableForDevelopment	235247000	USD
CY2010Q4	us-gaap	Liabilities Liabilities	10592078000	USD
CY2011Q4	us-gaap	Liabilities Liabilities	10380042000	USD
CY2010Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	16184194000	USD
CY2011Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	16659303000	USD
CY2010Q4	us-gaap	Liabilities Fair Value Disclosure LiabilitiesFairValueDisclosure	97210000	USD
CY2011Q4	us-gaap	Liabilities Fair Value Disclosure LiabilitiesFairValueDisclosure	103704000	USD
CY2010Q4	us-gaap	Line Of Credit LineOfCredit	0	USD
CY2011Q4	us-gaap	Line Of Credit LineOfCredit	0	USD
CY2010Q4	us-gaap	Line Of Credit Facility Amount Outstanding LineOfCreditFacilityAmountOutstanding	0	USD
CY2011Q4	us-gaap	Line Of Credit Facility Amount Outstanding LineOfCreditFacilityAmountOutstanding	0	USD
CY2012Q1	us-gaap	Line Of Credit Facility Current Borrowing Capacity LineOfCreditFacilityCurrentBorrowingCapacity	1250000000	USD
CY2012Q1	us-gaap	Line Of Credit Facility Maximum Borrowing Capacity LineOfCreditFacilityMaximumBorrowingCapacity	1750000000	USD
CY2009	us-gaap	Loans Assumed1 LoansAssumed1	0	USD
CY2010	us-gaap	Loans Assumed1 LoansAssumed1	359082000	USD
CY2011	us-gaap	Loans Assumed1 LoansAssumed1	158240000	USD
CY2011Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	5782526000	USD
CY2011Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	1161582000	USD
CY2011Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	1190038000	USD
CY2011Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	418900000	USD
CY2011Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	588340000	USD
CY2011Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	579675000	USD
CY2011	us-gaap	Loss Contingency Accrual Carrying Value Payments LossContingencyAccrualCarryingValuePayments	2300000	USD
CY2011	us-gaap	Loss Contingency Accrual Carrying Value Provision LossContingencyAccrualCarryingValueProvision	100000	USD
CY2009	us-gaap	Management Fees Revenue ManagementFeesRevenue	10346000	USD
CY2010	us-gaap	Management Fees Revenue ManagementFeesRevenue	9476000	USD
CY2011	us-gaap	Management Fees Revenue ManagementFeesRevenue	9026000	USD
CY2010Q4	us-gaap	Minority Interest MinorityInterest	118390000	USD
CY2011Q4	us-gaap	Minority Interest MinorityInterest	193842000	USD
CY2010	us-gaap	Minority Interest Change In Redemption Value MinorityInterestChangeInRedemptionValue	129918000	USD
CY2009	us-gaap	Minority Interest Change In Redemption Value MinorityInterestChangeInRedemptionValue	14544000	USD
CY2011	us-gaap	Minority Interest Change In Redemption Value MinorityInterestChangeInRedemptionValue	22714000	USD
CY2009	us-gaap	Minority Interest In Net Income Loss Operating Partnerships MinorityInterestInNetIncomeLossOperatingPartnerships	20305000	USD
CY2011	us-gaap	Minority Interest In Net Income Loss Operating Partnerships MinorityInterestInNetIncomeLossOperatingPartnerships	40780000	USD
CY2010	us-gaap	Minority Interest In Net Income Loss Operating Partnerships MinorityInterestInNetIncomeLossOperatingPartnerships	13099000	USD
CY2011	us-gaap	Minority Interest In Net Income Loss Preferred Unit Holders MinorityInterestInNetIncomeLossPreferredUnitHolders	0	USD
CY2009	us-gaap	Minority Interest In Net Income Loss Preferred Unit Holders MinorityInterestInNetIncomeLossPreferredUnitHolders	9000	USD
CY2010	us-gaap	Minority Interest In Net Income Loss Preferred Unit Holders MinorityInterestInNetIncomeLossPreferredUnitHolders	0	USD
CY2010Q4	us-gaap	Minority Interest In Operating Partnerships MinorityInterestInOperatingPartnerships	110399000	USD
CY2011Q4	us-gaap	Minority Interest In Operating Partnerships MinorityInterestInOperatingPartnerships	119536000	USD
CY2011Q4	us-gaap	Minority Interest Ownership Percentage By Parent MinorityInterestOwnershipPercentageByParent	0.957
CY2011	us-gaap	Mortgage Loans On Real Estate New Mortgage Loans MortgageLoansOnRealEstateNewMortgageLoans	190900000	USD
CY2010	us-gaap	Mortgage Loans On Real Estate New Mortgage Loans MortgageLoansOnRealEstateNewMortgageLoans	173600000	USD
CY2011	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-650993000	USD
CY2010	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	151541000	USD
CY2009	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-1473547000	USD
CY2010	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-639458000	USD
CY2009	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	105229000	USD
CY2011	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-194828000	USD
CY2010	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	726037000	USD
CY2011	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	798334000	USD
CY2009	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	670812000	USD
CY2010	us-gaap	Net Income Loss NetIncomeLoss	283610000	USD
CY2011	us-gaap	Net Income Loss NetIncomeLoss	893585000	USD
CY2009	us-gaap	Net Income Loss NetIncomeLoss	362273000	USD
CY2009	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	347794000	USD
CY2011	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	879720000	USD
CY2010	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	269242000	USD
CY2010Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	6343000	USD
CY2010Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	25166000	USD
CY2010Q4	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	185870000	USD
CY2010Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	51863000	USD
CY2011Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	552457000	USD
CY2011Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	123865000	USD
CY2011Q4	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	99016000	USD
CY2011Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	104382000	USD
CY2010	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	269242000	USD
CY2011	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	920500000	USD
CY2009	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	347794000	USD
CY2011	us-gaap	Noncash Or Part Noncash Acquisition Debt Assumed1 NoncashOrPartNoncashAcquisitionDebtAssumed1	158200000	USD
CY2010	us-gaap	Noncash Or Part Noncash Acquisition Debt Assumed1 NoncashOrPartNoncashAcquisitionDebtAssumed1	359100000	USD
CY2009	us-gaap	Noncash Project Abandonment Costs NoncashProjectAbandonmentCosts	4838000	USD
CY2010	us-gaap	Noncash Project Abandonment Costs NoncashProjectAbandonmentCosts	5272000	USD
CY2011	us-gaap	Noncash Project Abandonment Costs NoncashProjectAbandonmentCosts	5075000	USD
CY2010Q4	us-gaap	Notes Payable NotesPayable	5185180000	USD
CY2011Q4	us-gaap	Notes Payable NotesPayable	5609574000	USD
CY2011Q4	us-gaap	Notional Amount Of Interest Rate Derivatives NotionalAmountOfInterestRateDerivatives	300000000	USD
CY2010Q4	us-gaap	Notional Amount Of Interest Rate Derivatives NotionalAmountOfInterestRateDerivatives	300000000	USD
CY2011Q4	us-gaap	Number Of Real Estate Properties NumberOfRealEstateProperties	427
CY2011Q4	us-gaap	Number Of States In Which Entity Operates NumberOfStatesInWhichEntityOperates	15
CY2011Q4	us-gaap	Number Of Units In Real Estate Property NumberOfUnitsInRealEstateProperty	121974
CY2011	us-gaap	Operating Income Loss OperatingIncomeLoss	564860000	USD
CY2009	us-gaap	Operating Income Loss OperatingIncomeLoss	424518000	USD
CY2010	us-gaap	Operating Income Loss OperatingIncomeLoss	368690000	USD
CY2010Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	102631000	USD
CY2010Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	95644000	USD
CY2010Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	95837000	USD
CY2010Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	74578000	USD
CY2011Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	141104000	USD
CY2011Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	159953000	USD
CY2011Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	147850000	USD
CY2011Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	115953000	USD
CY2011Q4	us-gaap	Operating Leases Future Minimum Payments Due OperatingLeasesFutureMinimumPaymentsDue	740550000	USD
CY2011Q4	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	6445000	USD
CY2011Q4	us-gaap	Operating Leases Future Minimum Payments Due In Five Years OperatingLeasesFutureMinimumPaymentsDueInFiveYears	9196000	USD
CY2011Q4	us-gaap	Operating Leases Future Minimum Payments Due In Four Years OperatingLeasesFutureMinimumPaymentsDueInFourYears	9241000	USD
CY2011Q4	us-gaap	Operating Leases Future Minimum Payments Due In Three Years OperatingLeasesFutureMinimumPaymentsDueInThreeYears	8550000	USD
CY2011Q4	us-gaap	Operating Leases Future Minimum Payments Due In Two Years OperatingLeasesFutureMinimumPaymentsDueInTwoYears	7159000	USD
CY2011Q4	us-gaap	Operating Leases Future Minimum Payments Due Thereafter OperatingLeasesFutureMinimumPaymentsDueThereafter	699959000	USD
CY2011	us-gaap	Operating Leases Income Statement Lease Revenue OperatingLeasesIncomeStatementLeaseRevenue	1960243000	USD
CY2009	us-gaap	Operating Leases Income Statement Lease Revenue OperatingLeasesIncomeStatementLeaseRevenue	1610469000	USD
CY2010	us-gaap	Operating Leases Income Statement Lease Revenue OperatingLeasesIncomeStatementLeaseRevenue	1744768000	USD
CY2010	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	7600000	USD
CY2009	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	8400000	USD
CY2011	us-gaap	Operating Leases Rent Expense Net OperatingLeasesRentExpenseNet	7100000	USD
CY2011Q4	us-gaap	Operating Loss Carryforwards OperatingLossCarryforwards	71400000	USD
CY2011	us-gaap	Operating Loss Carryforwards Expiration Dates OperatingLossCarryforwardsExpirationDates	2028 and 2031
CY2011Q4	us-gaap	Other Assets OtherAssets	187155000	USD
CY2010Q4	us-gaap	Other Assets OtherAssets	148992000	USD
CY2010Q4	us-gaap	Other Assets Fair Value Disclosure OtherAssetsFairValueDisclosure	1194000	USD
CY2011Q4	us-gaap	Other Assets Fair Value Disclosure OtherAssetsFairValueDisclosure	1550000	USD
CY2010	us-gaap	Other Comprehensive Income Loss Net Of Tax Period Increase Decrease OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease	-62499000	USD
CY2011	us-gaap	Other Comprehensive Income Loss Net Of Tax Period Increase Decrease OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease	-138900000	USD
CY2009	us-gaap	Other Comprehensive Income Loss Net Of Tax Period Increase Decrease OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease	40480000	USD
CY2010	us-gaap	Other Comprehensive Income Other Net Of Tax OtherComprehensiveIncomeOtherNetOfTax	0	USD
CY2011	us-gaap	Other Comprehensive Income Other Net Of Tax OtherComprehensiveIncomeOtherNetOfTax	0	USD
CY2009	us-gaap	Other Comprehensive Income Other Net Of Tax OtherComprehensiveIncomeOtherNetOfTax	449000	USD
CY2010	us-gaap	Other Comprehensive Income Reclassification Adjustment For Sale Of Securities Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecuritiesIncludedInNetIncomeNetOfTax	0	USD
CY2009	us-gaap	Other Comprehensive Income Reclassification Adjustment For Sale Of Securities Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecuritiesIncludedInNetIncomeNetOfTax	4943000	USD
CY2011	us-gaap	Other Comprehensive Income Reclassification Adjustment For Sale Of Securities Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecuritiesIncludedInNetIncomeNetOfTax	0	USD
CY2009	us-gaap	Other Comprehensive Income Reclassification Adjustment On Derivatives Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentOnDerivativesIncludedInNetIncomeNetOfTax	-3724000	USD
CY2010	us-gaap	Other Comprehensive Income Reclassification Adjustment On Derivatives Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentOnDerivativesIncludedInNetIncomeNetOfTax	-3338000	USD
CY2011	us-gaap	Other Comprehensive Income Reclassification Adjustment On Derivatives Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentOnDerivativesIncludedInNetIncomeNetOfTax	-4343000	USD
CY2011	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	-143598000	USD
CY2010	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	-65894000	USD
CY2009	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	37676000	USD
CY2011	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	355000	USD
CY2009	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	3574000	USD
CY2010	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	57000	USD
CY2011Q4	us-gaap	Other Liabilities OtherLiabilities	291289000	USD
CY2010Q4	us-gaap	Other Liabilities OtherLiabilities	304202000	USD
CY2010Q4	us-gaap	Other Liabilities Fair Value Disclosure OtherLiabilitiesFairValueDisclosure	58132000	USD
CY2011Q4	us-gaap	Other Liabilities Fair Value Disclosure OtherLiabilitiesFairValueDisclosure	71426000	USD
CY2009	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	6477000	USD
CY2011	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	14557000	USD
CY2010	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	11928000	USD
CY2009	us-gaap	Owned Property Management Costs OwnedPropertyManagementCosts	71300000	USD
CY2011	us-gaap	Owned Property Management Costs OwnedPropertyManagementCosts	82133000	USD
CY2010	us-gaap	Owned Property Management Costs OwnedPropertyManagementCosts	80087000	USD
CY2009	us-gaap	Payments For Capital Improvements PaymentsForCapitalImprovements	123937000	USD
CY2011	us-gaap	Payments For Capital Improvements PaymentsForCapitalImprovements	144452000	USD
CY2010	us-gaap	Payments For Capital Improvements PaymentsForCapitalImprovements	138208000	USD
CY2010	us-gaap	Payments For Proceeds From Deposits On Real Estate Acquisitions PaymentsForProceedsFromDepositsOnRealEstateAcquisitions	-137106000	USD
CY2009	us-gaap	Payments For Proceeds From Deposits On Real Estate Acquisitions PaymentsForProceedsFromDepositsOnRealEstateAcquisitions	250257000	USD
CY2011	us-gaap	Payments For Proceeds From Deposits On Real Estate Acquisitions PaymentsForProceedsFromDepositsOnRealEstateAcquisitions	-7631000	USD
CY2011	us-gaap	Payments For Proceeds From Hedge Financing Activities PaymentsForProceedsFromHedgeFinancingActivities	147306000	USD
CY2010	us-gaap	Payments For Proceeds From Hedge Financing Activities PaymentsForProceedsFromHedgeFinancingActivities	10040000	USD
CY2009	us-gaap	Payments For Proceeds From Hedge Financing Activities PaymentsForProceedsFromHedgeFinancingActivities	-11253000	USD
CY2010	us-gaap	Payments For Proceeds From Mortgage Deposits PaymentsForProceedsFromMortgageDeposits	-73232000	USD
CY2011	us-gaap	Payments For Proceeds From Mortgage Deposits PaymentsForProceedsFromMortgageDeposits	-16596000	USD
CY2009	us-gaap	Payments For Proceeds From Mortgage Deposits PaymentsForProceedsFromMortgageDeposits	-46664000	USD
CY2010	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	1887000	USD
CY2009	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	1124000	USD
CY2011	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	0	USD
CY2009	us-gaap	Payments For Repurchase Of Preferred Stock And Preference Stock PaymentsForRepurchaseOfPreferredStockAndPreferenceStock	0	USD
CY2010	us-gaap	Payments For Repurchase Of Preferred Stock And Preference Stock PaymentsForRepurchaseOfPreferredStockAndPreferenceStock	877000	USD
CY2011	us-gaap	Payments For Repurchase Of Preferred Stock And Preference Stock PaymentsForRepurchaseOfPreferredStockAndPreferenceStock	0	USD
CY2010	us-gaap	Payments Of Debt Extinguishment Costs PaymentsOfDebtExtinguishmentCosts	1000000	USD
CY2010	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	379969000	USD
CY2011	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	432023000	USD
CY2010Q4	us-gaap	Preferred Stock Value Outstanding PreferredStockValueOutstanding	200000000	USD
CY2011Q4	us-gaap	Preferred Stock Value Outstanding PreferredStockValueOutstanding	200000000	USD
CY2009	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	488604000	USD
CY2010	us-gaap	Payments Of Dividends Minority Interest PaymentsOfDividendsMinorityInterest	18867000	USD
CY2009	us-gaap	Payments Of Dividends Minority Interest PaymentsOfDividendsMinorityInterest	28935000	USD
CY2011	us-gaap	Payments Of Dividends Minority Interest PaymentsOfDividendsMinorityInterest	20002000	USD
CY2011	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	12829000	USD
CY2010	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	14471000	USD
CY2009	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	14479000	USD
CY2010	us-gaap	Payments Of Financing Costs PaymentsOfFinancingCosts	8811000	USD
CY2011	us-gaap	Payments Of Financing Costs PaymentsOfFinancingCosts	20421000	USD
CY2009	us-gaap	Payments Of Financing Costs PaymentsOfFinancingCosts	9291000	USD
CY2011	us-gaap	Payments Of Merger Related Costs Financing Activities PaymentsOfMergerRelatedCostsFinancingActivities	2600000	USD
CY2011	us-gaap	Payments Of Stock Issuance Costs PaymentsOfStockIssuanceCosts	3596000	USD
CY2010	us-gaap	Payments Of Stock Issuance Costs PaymentsOfStockIssuanceCosts	4657000	USD
CY2009	us-gaap	Payments Of Stock Issuance Costs PaymentsOfStockIssuanceCosts	2536000	USD
CY2009	us-gaap	Payments To Acquire Additional Interest In Subsidiaries PaymentsToAcquireAdditionalInterestInSubsidiaries	11480000	USD
CY2011	us-gaap	Payments To Acquire Additional Interest In Subsidiaries PaymentsToAcquireAdditionalInterestInSubsidiaries	12809000	USD
CY2010	us-gaap	Payments To Acquire Additional Interest In Subsidiaries PaymentsToAcquireAdditionalInterestInSubsidiaries	16023000	USD
CY2009	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	0	USD
CY2011	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	0	USD
CY2010	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	26854000	USD
CY2009	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	0	USD
CY2010	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	0	USD
CY2011	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	2021000	USD
CY2010	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	0	USD
CY2011	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	0	USD
CY2009	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	77822000	USD
CY2010	us-gaap	Payments To Acquire Real Estate PaymentsToAcquireRealEstate	1189210000	USD
CY2009	us-gaap	Payments To Acquire Real Estate PaymentsToAcquireRealEstate	175531000	USD
CY2011	us-gaap	Payments To Acquire Real Estate PaymentsToAcquireRealEstate	1441599000	USD
CY2009	us-gaap	Payments To Develop Real Estate Assets PaymentsToDevelopRealEstateAssets	330623000	USD
CY2010	us-gaap	Payments To Develop Real Estate Assets PaymentsToDevelopRealEstateAssets	131301000	USD
CY2011	us-gaap	Payments To Develop Real Estate Assets PaymentsToDevelopRealEstateAssets	120741000	USD
CY2010Q4	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0.01
CY2011Q4	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0.01
CY2010Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	100000000	shares
CY2011Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	100000000	shares
CY2010Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	1600000	shares
CY2011Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	1600000	shares
CY2011Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	1600000	shares
CY2010Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	1600000	shares
CY2010Q4	us-gaap	Preferred Stock Value PreferredStockValue	200000000	USD
CY2011Q4	us-gaap	Preferred Stock Value PreferredStockValue	200000000	USD
CY2010	us-gaap	Proceeds From Issuance Of Common Limited Partners Units ProceedsFromIssuanceOfCommonLimitedPartnersUnits	7400000	USD
CY2010	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	329452000	USD
CY2011	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	190905000	USD
CY2009	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	738798000	USD
CY2010	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	173561000	USD
CY2009	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	86184000	USD
CY2011	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	173484000	USD
CY2010	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans	5112000	USD
CY2011	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans	5262000	USD
CY2009	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans	5292000	USD
CY2009	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	893000	USD
CY2010	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	222000	USD
CY2011	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	75911000	USD
CY2009	us-gaap	Proceeds From Notes Payable ProceedsFromNotesPayable	0	USD
CY2010	us-gaap	Proceeds From Notes Payable ProceedsFromNotesPayable	595422000	USD
CY2011	us-gaap	Proceeds From Notes Payable ProceedsFromNotesPayable	996190000	USD
CY2009	us-gaap	Proceeds From Partnership Contribution ProceedsFromPartnershipContribution	78000	USD
CY2011	us-gaap	Proceeds From Partnership Contribution ProceedsFromPartnershipContribution	0	USD
CY2010	us-gaap	Proceeds From Partnership Contribution ProceedsFromPartnershipContribution	0	USD
CY2009	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-16000	USD
CY2010	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-48000	USD
CY2011	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-48000	USD
CY2011	us-gaap	Proceeds From Repayments Of Debt ProceedsFromRepaymentsOfDebt	991700000	USD
CY2010	us-gaap	Proceeds From Repayments Of Debt ProceedsFromRepaymentsOfDebt	652100000	USD
CY2009	us-gaap	Proceeds From Sale And Maturity Of Marketable Securities ProceedsFromSaleAndMaturityOfMarketableSecurities	215753000	USD
CY2011	us-gaap	Proceeds From Sale And Maturity Of Marketable Securities ProceedsFromSaleAndMaturityOfMarketableSecurities	0	USD
CY2010	us-gaap	Proceeds From Sale And Maturity Of Marketable Securities ProceedsFromSaleAndMaturityOfMarketableSecurities	25000000	USD
CY2009	us-gaap	Proceeds From Sale Of Real Estate Heldforinvestment ProceedsFromSaleOfRealEstateHeldforinvestment	887055000	USD
CY2011	us-gaap	Proceeds From Sale Of Real Estate Heldforinvestment ProceedsFromSaleOfRealEstateHeldforinvestment	1500583000	USD
CY2010	us-gaap	Proceeds From Sale Of Real Estate Heldforinvestment ProceedsFromSaleOfRealEstateHeldforinvestment	672700000	USD
CY2011	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	95322000	USD
CY2010	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	71596000	USD
CY2009	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	9136000	USD
CY2009	us-gaap	Profit Loss ProfitLoss	382029000	USD
CY2010	us-gaap	Profit Loss ProfitLoss	295983000	USD
CY2011	us-gaap	Profit Loss ProfitLoss	935197000	USD
CY2010Q4	us-gaap	Profit Loss ProfitLoss	198212000	USD
CY2010Q2	us-gaap	Profit Loss ProfitLoss	10089000	USD
CY2010Q1	us-gaap	Profit Loss ProfitLoss	57856000	USD
CY2010Q3	us-gaap	Profit Loss ProfitLoss	29826000	USD
CY2011Q1	us-gaap	Profit Loss ProfitLoss	133066000	USD
CY2011Q4	us-gaap	Profit Loss ProfitLoss	107401000	USD
CY2011Q3	us-gaap	Profit Loss ProfitLoss	112977000	USD
CY2011Q2	us-gaap	Profit Loss ProfitLoss	581753000	USD
CY2010Q4	us-gaap	Property Plant And Equipment Fair Value Disclosure PropertyPlantAndEquipmentFairValueDisclosure	56000000	USD
CY2010Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	15226512000	USD
CY2011Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	15554740000	USD
CY2010Q4	us-gaap	Real Estate Accumulated Depreciation RealEstateAccumulatedDepreciation	4337357000	USD
CY2008Q4	us-gaap	Real Estate Accumulated Depreciation RealEstateAccumulatedDepreciation	3561300000	USD
CY2011Q4	us-gaap	Real Estate Accumulated Depreciation RealEstateAccumulatedDepreciation	4539583000	USD
CY2009Q4	us-gaap	Real Estate Accumulated Depreciation RealEstateAccumulatedDepreciation	3877564000	USD
CY2011	us-gaap	Real Estate Accumulated Depreciation Depreciation Expense RealEstateAccumulatedDepreciationDepreciationExpense	663616000	USD
CY2009	us-gaap	Real Estate Accumulated Depreciation Depreciation Expense RealEstateAccumulatedDepreciationDepreciationExpense	600375000	USD
CY2010	us-gaap	Real Estate Accumulated Depreciation Depreciation Expense RealEstateAccumulatedDepreciationDepreciationExpense	673403000	USD
CY2009Q4	us-gaap	Real Estate Gross At Carrying Value RealEstateGrossAtCarryingValue	18465144000	USD
CY2010Q4	us-gaap	Real Estate Gross At Carrying Value RealEstateGrossAtCarryingValue	19702371000	USD
CY2008Q4	us-gaap	Real Estate Gross At Carrying Value RealEstateGrossAtCarryingValue	18690239000	USD
CY2011Q4	us-gaap	Real Estate Gross At Carrying Value RealEstateGrossAtCarryingValue	20407946000	USD
CY2009	us-gaap	Real Estate Improvements RealEstateImprovements	125965000	USD
CY2011	us-gaap	Real Estate Improvements RealEstateImprovements	151476000	USD
CY2010	us-gaap	Real Estate Improvements RealEstateImprovements	141199000	USD
CY2011Q4	us-gaap	Real Estate Investment Property Accumulated Depreciation RealEstateInvestmentPropertyAccumulatedDepreciation	4539583000	USD
CY2010Q4	us-gaap	Real Estate Investment Property Accumulated Depreciation RealEstateInvestmentPropertyAccumulatedDepreciation	4337357000	USD
CY2011Q4	us-gaap	Real Estate Investment Property At Cost RealEstateInvestmentPropertyAtCost	20407946000	USD
CY2010Q4	us-gaap	Real Estate Investment Property At Cost RealEstateInvestmentPropertyAtCost	19702371000	USD
CY2010Q4	us-gaap	Real Estate Investment Property Net RealEstateInvestmentPropertyNet	15365014000	USD
CY2011Q4	us-gaap	Real Estate Investment Property Net RealEstateInvestmentPropertyNet	15868363000	USD
CY2009	us-gaap	Real Estate Taxes And Insurance RealEstateTaxesAndInsurance	187895000	USD
CY2010	us-gaap	Real Estate Taxes And Insurance RealEstateTaxesAndInsurance	209023000	USD
CY2011	us-gaap	Real Estate Taxes And Insurance RealEstateTaxesAndInsurance	219743000	USD
CY2011	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	0	USD
CY2010	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	0	USD
CY2009	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	4943000	USD
CY2009	us-gaap	Related Party Transaction Expenses From Transactions With Related Party RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty	3020155	USD
CY2010	us-gaap	Related Party Transaction Expenses From Transactions With Related Party RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty	2661805	USD
CY2011	us-gaap	Related Party Transaction Expenses From Transactions With Related Party RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty	2184377	USD
CY2009	us-gaap	Repayments Of Lines Of Credit RepaymentsOfLinesOfCredit	0	USD
CY2011	us-gaap	Repayments Of Lines Of Credit RepaymentsOfLinesOfCredit	1455000000	USD
CY2010	us-gaap	Repayments Of Lines Of Credit RepaymentsOfLinesOfCredit	5513125000	USD
CY2011	us-gaap	Repayments Of Notes Payable RepaymentsOfNotesPayable	575641000	USD
CY2010	us-gaap	Repayments Of Notes Payable RepaymentsOfNotesPayable	0	USD
CY2009	us-gaap	Repayments Of Notes Payable RepaymentsOfNotesPayable	850115000	USD
CY2010Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	180987000	USD
CY2011Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	152237000	USD
CY2010Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	203581000	USD
CY2011Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	615572000	USD
CY2009	us-gaap	Revenues Revenues	1620815000	USD
CY2011	us-gaap	Revenues Revenues	1969269000	USD
CY2010	us-gaap	Revenues Revenues	1754244000	USD
CY2010Q1	us-gaap	Sales Revenue Net SalesRevenueNet	416844000	USD
CY2010Q2	us-gaap	Sales Revenue Net SalesRevenueNet	434499000	USD
CY2010Q4	us-gaap	Sales Revenue Net SalesRevenueNet	455967000	USD
CY2010Q3	us-gaap	Sales Revenue Net SalesRevenueNet	446934000	USD
CY2011Q1	us-gaap	Sales Revenue Net SalesRevenueNet	466356000	USD
CY2011Q2	us-gaap	Sales Revenue Net SalesRevenueNet	484290000	USD
CY2011Q3	us-gaap	Sales Revenue Net SalesRevenueNet	504496000	USD
CY2011Q4	us-gaap	Sales Revenue Net SalesRevenueNet	514127000	USD
CY2010Q4	us-gaap	Secured Debt SecuredDebt	4762896000	USD
CY2011Q4	us-gaap	Secured Debt SecuredDebt	4111487000	USD
CY2011Q4	us-gaap	Security Deposit Liability SecurityDepositLiability	65286000	USD
CY2010Q4	us-gaap	Security Deposit Liability SecurityDepositLiability	60812000	USD
CY2009	us-gaap	Segment Reporting Information Revenue SegmentReportingInformationRevenue	1610469000	USD
CY2010	us-gaap	Segment Reporting Information Revenue SegmentReportingInformationRevenue	1744768000	USD
CY2011	us-gaap	Segment Reporting Information Revenue SegmentReportingInformationRevenue	1960243000	USD
CY2011	us-gaap	Service Management Costs ServiceManagementCosts	4279000	USD
CY2010	us-gaap	Service Management Costs ServiceManagementCosts	4998000	USD
CY2009	us-gaap	Service Management Costs ServiceManagementCosts	7345000	USD
CY2009	us-gaap	Share Based Compensation ShareBasedCompensation	17843000	USD
CY2011	us-gaap	Share Based Compensation ShareBasedCompensation	21177000	USD
CY2010	us-gaap	Share Based Compensation ShareBasedCompensation	18875000	USD
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Award Expiration Dating ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardExpirationDating	ten years from the date of grant
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Discount From Market Price Purchase Date ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPricePurchaseDate	0.85
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	-126960	shares
CY2009	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	-64280	shares
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	-35038	shares
CY2010Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageGrantDateFairValue	30.84
CY2011Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageGrantDateFairValue	37.19
CY2009Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageGrantDateFairValue	35.28
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	270805	shares
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	170588	shares
CY2009	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	362997	shares
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	53.99
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	34.85
CY2009	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	22.62
CY2009Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	954366	shares
CY2008Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	996011	shares
CY2011Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	697510	shares
CY2010Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	911950	shares
CY2008Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	44.16
CY2009Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	37.10
CY2010Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	32.05
CY2011Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	34.17
CY2009	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	-340362	shares
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	-278183	shares
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	-258068	shares
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	9100000	USD
CY2009	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	8000000	USD
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	14000000	USD
CY2009	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	42.67
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	52.25
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	38.32
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.0456
CY2009	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.0468
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.0485
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Term ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedTerm	5
CY2009	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Term ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedTerm	5
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Term ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedTerm	5
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.324
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.271
CY2009	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.268
CY2009	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.0189
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.0227
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.0229
CY2011Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized	12980741	shares
CY2011Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	12473580	shares
CY2010Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber	6786651	shares
CY2009Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber	7974815	shares
CY2009Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	33.55
CY2010Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	34.89
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Remaining Contractual Term ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm	4.5
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	39600000	USD
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	74800000	USD
CY2009	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	2800000	USD
CY2009Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	21.62
CY2010Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	28.68
CY2011Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	32.27
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod	-16270	shares
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod	-96457	shares
CY2009	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod	-95650	shares
CY2010Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice	42.69
CY2009Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice	32.21
CY2011Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice	44.13
CY2009	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	-146151	shares
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	-41559	shares
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	-76275	shares
CY2009Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	30.07
CY2011Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	35.14
CY2010Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	29.43
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod	1491311	shares
CY2009	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod	2541005	shares
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod	1436115	shares
CY2010Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	33.59
CY2011Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	53.70
CY2009Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	23.08
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	8.36
CY2009	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	3.38
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	6.18
CY2009Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	11349750	shares
CY2008Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	9473259	shares
CY2011Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	8594020	shares
CY2010Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	10106488	shares
CY2010Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	33.00
CY2011Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	36.81
CY2008Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	33.94
CY2009Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	32.03
CY2011Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Aggregate Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue	173200000	USD
CY2011Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber	8507188	shares
CY2011Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice	36.68
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Weighted Average Remaining Contractual Term ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm	5.91
CY2010	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Shares Issued In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod	157363	shares
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Shares Issued In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod	113107	shares
CY2009	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Shares Issued In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod	324394	shares
CY2011	us-gaap	Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Lower Range Limit ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit	18.70
CY2011Q4	us-gaap	Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Number Of Exercisable Options ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions	5415550	shares
CY2011Q4	us-gaap	Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Number Of Outstanding Options ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions	8594020	shares
CY2011	us-gaap	Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Upper Range Limit ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit	62.32
CY2011Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1	121300000	USD
CY2011Q4	us-gaap	Sharebased Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Exercisable Options Weighted Average Exercise Price1 SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1	34.64
CY2011Q4	us-gaap	Sharebased Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Outstanding Options Weighted Average Exercise Price Beginning Balance1 SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1	36.81
CY2011Q4	us-gaap	Sharebased Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Outstanding Options Weighted Average Remaining Contractual Term1 SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm1	5.94
CY2010	us-gaap	Stock Issued During Period Shares Conversion Of Units StockIssuedDuringPeriodSharesConversionOfUnits	884472	shares
CY2009	us-gaap	Stock Issued During Period Shares Conversion Of Units StockIssuedDuringPeriodSharesConversionOfUnits	2676002	shares
CY2011	us-gaap	Stock Issued During Period Shares Conversion Of Units StockIssuedDuringPeriodSharesConversionOfUnits	341594	shares
CY2009	us-gaap	Stock Issued During Period Shares Employee Stock Purchase Plans StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans	324394	shares
CY2011	us-gaap	Stock Issued During Period Shares Employee Stock Purchase Plans StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans	113107	shares
CY2010	us-gaap	Stock Issued During Period Shares Employee Stock Purchase Plans StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans	157363	shares
CY2010	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	6200000	shares
CY2009	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	3500000	shares
CY2011	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	3866666	shares
CY2009	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	422713	shares
CY2011	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	2945948	shares
CY2010	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	2506645	shares
CY2011	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	201941887	USD
CY2010	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	291900000	USD
CY2009	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	123700000	USD
CY2011	us-gaap	Stock Repurchase Program Remaining Authorized Repurchase Amount StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount	464600000	USD
CY2010Q4	us-gaap	Stockholders Equity StockholdersEquity	5090186000	USD
CY2011Q4	us-gaap	Stockholders Equity StockholdersEquity	5669015000	USD
CY2010Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	5208576000	USD
CY2011Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	5862857000	USD
CY2010	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	32.46
CY2009	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	23.69
CY2011	us-gaap	Unrealized Gain Loss On Derivatives UnrealizedGainLossOnDerivatives	-186000	USD
CY2009	us-gaap	Unrealized Gain Loss On Derivatives UnrealizedGainLossOnDerivatives	3000	USD
CY2010	us-gaap	Unrealized Gain Loss On Derivatives UnrealizedGainLossOnDerivatives	-1000	USD
CY2011	us-gaap	Unrealized Gain Loss On Interest Rate Cash Flow Hedges Pretax Accumulated Other Comprehensive Income Loss UnrealizedGainLossOnInterestRateCashFlowHedgesPretaxAccumulatedOtherComprehensiveIncomeLoss	197600000	USD
CY2010	us-gaap	Unrealized Gain Loss On Interest Rate Cash Flow Hedges Pretax Accumulated Other Comprehensive Income Loss UnrealizedGainLossOnInterestRateCashFlowHedgesPretaxAccumulatedOtherComprehensiveIncomeLoss	58300000	USD
CY2011	us-gaap	Use Of Estimates UseOfEstimates	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:17px;text-align:left;text-indent:24px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-style:italic;">Use of Estimates</font></div><div style="line-height:120%;padding-top:9px;text-align:justify;text-indent:48px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">In preparation of the Company’s financial statements in conformity with accounting principles generally accepted in the United States, management makes estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements as well as the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates.</font></div></div>
CY2009	us-gaap	Weighted Average Limited Partnership And General Partnership Units Outstanding Basic WeightedAverageLimitedPartnershipAndGeneralPartnershipUnitsOutstandingBasic	289167000	shares
CY2011	us-gaap	Weighted Average Limited Partnership And General Partnership Units Outstanding Basic WeightedAverageLimitedPartnershipAndGeneralPartnershipUnitsOutstandingBasic	308062000	shares
CY2010	us-gaap	Weighted Average Limited Partnership And General Partnership Units Outstanding Basic WeightedAverageLimitedPartnershipAndGeneralPartnershipUnitsOutstandingBasic	296527000	shares
CY2010	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	282888000	shares
CY2011	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	312065000	shares
CY2009	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	273609000	shares
CY2010Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	282217000	shares
CY2010Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	282717000	shares
CY2010Q4	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	285916000	shares
CY2010Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	280645000	shares
CY2011Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	292895000	shares
CY2011Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	312844000	shares
CY2011Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	312199000	shares
CY2011Q4	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	312731000	shares
CY2011	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	294856000	shares
CY2009	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	273609000	shares
CY2010	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	282888000	shares
CY2010Q4	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	285916000	shares
CY2010Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	282217000	shares
CY2010Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	282717000	shares
CY2010Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	280645000	shares
CY2011Q4	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	295990000	shares
CY2011Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	292895000	shares
CY2011Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	295831000	shares
CY2011Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	294663000	shares
CY2010Q4	eqr	Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrentOtherThanInterestAndDividendPayable	39452000	USD
CY2011Q4	eqr	Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrentOtherThanInterestAndDividendPayable	35206000	USD
CY2011Q4	eqr	Additional Common Shares Authorized AdditionalCommonSharesAuthorized	9172314	shares
CY2012Q1	eqr	Additional Shares Available Subsequent Balance Sheet Date AdditionalSharesAvailableSubsequentBalanceSheetDate	7096956	shares
CY2011	eqr	Adjustment Depreciation AdjustmentDepreciation	663616000	USD
CY2009	eqr	Adjustment Depreciation AdjustmentDepreciation	600375000	USD
CY2010	eqr	Adjustment Depreciation AdjustmentDepreciation	673403000	USD
CY2010	eqr	Allocation Of Net Income Loss To Non Controlling Interests Partially Owned Properties AllocationOfNetIncomeLossToNonControllingInterestsPartiallyOwnedProperties	726000	USD
CY2011	eqr	Allocation Of Net Income Loss To Non Controlling Interests Partially Owned Properties AllocationOfNetIncomeLossToNonControllingInterestsPartiallyOwnedProperties	-832000	USD
CY2009	eqr	Allocation Of Net Income Loss To Non Controlling Interests Partially Owned Properties AllocationOfNetIncomeLossToNonControllingInterestsPartiallyOwnedProperties	558000	USD
CY2009	eqr	Allocation Of Net Income Loss To Noncontrolling Interests Partially Owned Properties AllocationOfNetIncomeLossToNoncontrollingInterestsPartiallyOwnedProperties	-558000	USD
CY2010	eqr	Allocation Of Net Income Loss To Noncontrolling Interests Partially Owned Properties AllocationOfNetIncomeLossToNoncontrollingInterestsPartiallyOwnedProperties	-726000	USD
CY2011	eqr	Allocation Of Net Income Loss To Noncontrolling Interests Partially Owned Properties AllocationOfNetIncomeLossToNoncontrollingInterestsPartiallyOwnedProperties	832000	USD
CY2010	eqr	Amortization Of Deferred Financing Costs AmortizationOfDeferredFinancingCosts	10406000	USD
CY2009	eqr	Amortization Of Deferred Financing Costs AmortizationOfDeferredFinancingCosts	13127000	USD
CY2011	eqr	Amortization Of Deferred Financing Costs AmortizationOfDeferredFinancingCosts	17846000	USD
CY2011	eqr	Amortization Of Deferred Financing Costs Deferred Financing Costs Net AmortizationOfDeferredFinancingCostsDeferredFinancingCostsNet	17846000	USD
CY2009	eqr	Amortization Of Deferred Financing Costs Deferred Financing Costs Net AmortizationOfDeferredFinancingCostsDeferredFinancingCostsNet	16712000	USD
CY2010	eqr	Amortization Of Deferred Financing Costs Deferred Financing Costs Net AmortizationOfDeferredFinancingCostsDeferredFinancingCostsNet	13174000	USD
CY2009	eqr	Amortization Of Deferred Financing Costs Investment In Real Estate Net AmortizationOfDeferredFinancingCostsInvestmentInRealEstateNet	-3585000	USD
CY2011	eqr	Amortization Of Deferred Financing Costs Investment In Real Estate Net AmortizationOfDeferredFinancingCostsInvestmentInRealEstateNet	0	USD
CY2010	eqr	Amortization Of Deferred Financing Costs Investment In Real Estate Net AmortizationOfDeferredFinancingCostsInvestmentInRealEstateNet	-2768000	USD
CY2010	eqr	Consolidation Of Previously Unconsolidated Properties Deposits Restricted ConsolidationOfPreviouslyUnconsolidatedPropertiesDepositsRestricted	-42633000	USD
CY2010	eqr	Consolidation Of Previously Unconsolidated Properties Investment In Real Estate Net ConsolidationOfPreviouslyUnconsolidatedPropertiesInvestmentInRealEstateNet	-105065000	USD
CY2009	eqr	Amortization Of Deferred Settlements On Derivative Instruments Other Liabilities AmortizationOfDeferredSettlementsOnDerivativeInstrumentsOtherLiabilities	-1496000	USD
CY2011	eqr	Amortization Of Deferred Settlements On Derivative Instruments Other Liabilities AmortizationOfDeferredSettlementsOnDerivativeInstrumentsOtherLiabilities	-535000	USD
CY2010	eqr	Amortization Of Deferred Settlements On Derivative Instruments Other Liabilities AmortizationOfDeferredSettlementsOnDerivativeInstrumentsOtherLiabilities	-534000	USD
CY2009	eqr	Amortization Of Discounts And Premiums On Debt Investment In Real Estate Net AmortizationOfDiscountsAndPremiumsOnDebtInvestmentInRealEstateNet	-3000	USD
CY2010	eqr	Amortization Of Discounts And Premiums On Debt Investment In Real Estate Net AmortizationOfDiscountsAndPremiumsOnDebtInvestmentInRealEstateNet	0	USD
CY2011	eqr	Amortization Of Discounts And Premiums On Debt Investment In Real Estate Net AmortizationOfDiscountsAndPremiumsOnDebtInvestmentInRealEstateNet	0	USD
CY2009	eqr	Amortization Of Discounts And Premiums On Debt Mortgage Notes Payable AmortizationOfDiscountsAndPremiumsOnDebtMortgageNotesPayable	-6097000	USD
CY2010	eqr	Amortization Of Discounts And Premiums On Debt Mortgage Notes Payable AmortizationOfDiscountsAndPremiumsOnDebtMortgageNotesPayable	-9208000	USD
CY2011	eqr	Amortization Of Discounts And Premiums On Debt Mortgage Notes Payable AmortizationOfDiscountsAndPremiumsOnDebtMortgageNotesPayable	-8260000	USD
CY2010	eqr	Amortization Of Discounts And Premiums On Debt Notes Net AmortizationOfDiscountsAndPremiumsOnDebtNotesNet	8737000	USD
CY2009	eqr	Amortization Of Discounts And Premiums On Debt Notes Net AmortizationOfDiscountsAndPremiumsOnDebtNotesNet	11957000	USD
CY2011	eqr	Amortization Of Discounts And Premiums On Debt Notes Net AmortizationOfDiscountsAndPremiumsOnDebtNotesNet	6782000	USD
CY2011	eqr	Annual Dividend Per Depositary Share AnnualDividendPerDepositaryShare	1.62
CY2009	eqr	Annual Dividend Per Unit AnnualDividendPerUnit	1.17
CY2009	eqr	Average Price Per Common Share Issued AveragePricePerCommonShareIssued	35.38
CY2010	eqr	Average Price Per Common Share Issued AveragePricePerCommonShareIssued	47.45
CY2011	eqr	Average Price Per Common Share Issued AveragePricePerCommonShareIssued	52.23
CY2012Q1	eqr	Breakupfee Breakupfee	80000000	USD
CY2011Q4	eqr	Bridge Loan Principal Amount BridgeLoanPrincipalAmount	1000000000	USD
CY2010	eqr	Cash Consideration Equity Buyout CashConsiderationEquityBuyout	15300000	USD
CY2009	eqr	Cash Consideration Equity Buyout CashConsiderationEquityBuyout	2100000	USD
CY2010	eqr	Change In Mortgage Deposits ChangeInMortgageDeposits	-4699000	USD
CY2009	eqr	Change In Mortgage Deposits ChangeInMortgageDeposits	-2437000	USD
CY2011	eqr	Change In Mortgage Deposits ChangeInMortgageDeposits	-1901000	USD
CY2011	eqr	Common Shares Added To Atm Program CommonSharesAddedToAtmProgram	5700000	shares
CY2010Q4	eqr	Common Shares And Units Outstanding CommonSharesAndUnitsOutstanding	303809279	shares
CY2011Q4	eqr	Common Shares And Units Outstanding CommonSharesAndUnitsOutstanding	311000728	shares
CY2009Q4	eqr	Common Shares And Units Outstanding CommonSharesAndUnitsOutstanding	294157017	shares
CY2011	eqr	Common Stock Capital Shares Reserved For Future Issuance Under Share Offering Program CommonStockCapitalSharesReservedForFutureIssuanceUnderShareOfferingProgram	17000000	shares
CY2009	eqr	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest Partially Owned Properties ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterestPartiallyOwnedProperties	558000	USD
CY2011	eqr	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest Partially Owned Properties ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterestPartiallyOwnedProperties	-832000	USD
CY2010	eqr	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest Partially Owned Properties ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterestPartiallyOwnedProperties	726000	USD
CY2011Q4	eqr	Consideration From Shares Not Settled ConsiderationFromSharesNotSettled	28456929	USD
CY2009Q4	eqr	Consideration From Shares Not Settled ConsiderationFromSharesNotSettled	37600000	USD
CY2011Q4	eqr	Consolidated Project Under Development Commitment Fund ConsolidatedProjectUnderDevelopmentCommitmentFund	351200000	USD
CY2011	eqr	Consolidation Of Previously Unconsolidated Properties Deposits Restricted ConsolidationOfPreviouslyUnconsolidatedPropertiesDepositsRestricted	0	USD
CY2009	eqr	Consolidation Of Previously Unconsolidated Properties Deposits Restricted ConsolidationOfPreviouslyUnconsolidatedPropertiesDepositsRestricted	0	USD
CY2009	eqr	Consolidation Of Previously Unconsolidated Properties Investment In Real Estate Net ConsolidationOfPreviouslyUnconsolidatedPropertiesInvestmentInRealEstateNet	0	USD
CY2011	eqr	Consolidation Of Previously Unconsolidated Properties Investment In Real Estate Net ConsolidationOfPreviouslyUnconsolidatedPropertiesInvestmentInRealEstateNet	0	USD
CY2009	eqr	Consolidation Of Previously Unconsolidated Properties Investments In Unconsolidated Entities ConsolidationOfPreviouslyUnconsolidatedPropertiesInvestmentsInUnconsolidatedEntities	0	USD
CY2011	eqr	Consolidation Of Previously Unconsolidated Properties Investments In Unconsolidated Entities ConsolidationOfPreviouslyUnconsolidatedPropertiesInvestmentsInUnconsolidatedEntities	0	USD
CY2010	eqr	Consolidation Of Previously Unconsolidated Properties Investments In Unconsolidated Entities ConsolidationOfPreviouslyUnconsolidatedPropertiesInvestmentsInUnconsolidatedEntities	7376000	USD
CY2010	eqr	Consolidation Of Previously Unconsolidated Properties Mortgage Notes Payable ConsolidationOfPreviouslyUnconsolidatedPropertiesMortgageNotesPayable	112631000	USD
CY2009	eqr	Consolidation Of Previously Unconsolidated Properties Mortgage Notes Payable ConsolidationOfPreviouslyUnconsolidatedPropertiesMortgageNotesPayable	0	USD
CY2011	eqr	Consolidation Of Previously Unconsolidated Properties Mortgage Notes Payable ConsolidationOfPreviouslyUnconsolidatedPropertiesMortgageNotesPayable	0	USD
CY2011	eqr	Consolidation Of Previously Unconsolidated Properties Net Other Assets ConsolidationOfPreviouslyUnconsolidatedPropertiesNetOtherAssets	0	USD
CY2010	eqr	Consolidation Of Previously Unconsolidated Properties Net Other Assets ConsolidationOfPreviouslyUnconsolidatedPropertiesNetOtherAssets	837000	USD
CY2009	eqr	Consolidation Of Previously Unconsolidated Properties Net Other Assets ConsolidationOfPreviouslyUnconsolidatedPropertiesNetOtherAssets	0	USD
CY2010	eqr	Contract Value Per Op Unit ContractValuePerOpUnit	35.00
CY2011Q4	eqr	Contracted Acquisition Percent ContractedAcquisitionPercent	0.265
CY2011Q4	eqr	Contracted Aquisition Price ContractedAquisitionPrice	1325000000	USD
CY2009	eqr	Contribution Value Long Term Incentive Plan Unit ContributionValueLongTermIncentivePlanUnit	100000	USD
CY2010	eqr	Contribution Value Long Term Incentive Plan Unit ContributionValueLongTermIncentivePlanUnit	0	USD
CY2011	eqr	Contribution Value Long Term Incentive Plan Unit ContributionValueLongTermIncentivePlanUnit	0	USD
CY2009	eqr	Conversion Of Preference Units ConversionOfPreferenceUnits	7367	shares
CY2009	eqr	Conversion Of Restricted Shares To Ltip Units Shares ConversionOfRestrictedSharesToLtipUnitsShares	0	shares
CY2011	eqr	Conversion Of Restricted Shares To Ltip Units Shares ConversionOfRestrictedSharesToLtipUnitsShares	-101988	shares
CY2010	eqr	Conversion Of Restricted Shares To Ltip Units Shares ConversionOfRestrictedSharesToLtipUnitsShares	0	shares
CY2009	eqr	Conversion Price Preference Unit ConversionPricePreferenceUnit	24.50
CY2010	eqr	Conversion Price Preference Unit ConversionPricePreferenceUnit	0
CY2011	eqr	Conversion Price Preference Unit ConversionPricePreferenceUnit	0
CY2011	eqr	Conversion Price Series B Junior Preference Unit ConversionPriceSeriesBJuniorPreferenceUnit	0	USD
CY2010	eqr	Conversion Price Series B Junior Preference Unit ConversionPriceSeriesBJuniorPreferenceUnit	0	USD
CY2009	eqr	Conversion Price Series B Junior Preference Unit ConversionPriceSeriesBJuniorPreferenceUnit	200000	USD
CY2008Q4	eqr	Cumulative Effect On Notes From Adoption Of Accounting Principle CumulativeEffectOnNotesFromAdoptionOfAccountingPrinciple	17300000	USD
CY2010	eqr	Deconsolidation Of Previously Consolidated Properties Investment In Real Estate Net DeconsolidationOfPreviouslyConsolidatedPropertiesInvestmentInRealEstateNet	14875000	USD
CY2011	eqr	Deconsolidation Of Previously Consolidated Properties Investment In Real Estate Net DeconsolidationOfPreviouslyConsolidatedPropertiesInvestmentInRealEstateNet	35495000	USD
CY2009	eqr	Deconsolidation Of Previously Consolidated Properties Investment In Real Estate Net DeconsolidationOfPreviouslyConsolidatedPropertiesInvestmentInRealEstateNet	0	USD
CY2010	eqr	Deconsolidation Of Previously Consolidated Properties Investments In Unconsolidated Entities DeconsolidationOfPreviouslyConsolidatedPropertiesInvestmentsInUnconsolidatedEntities	-3167000	USD
CY2009	eqr	Deconsolidation Of Previously Consolidated Properties Investments In Unconsolidated Entities DeconsolidationOfPreviouslyConsolidatedPropertiesInvestmentsInUnconsolidatedEntities	0	USD
CY2011	eqr	Deconsolidation Of Previously Consolidated Properties Investments In Unconsolidated Entities DeconsolidationOfPreviouslyConsolidatedPropertiesInvestmentsInUnconsolidatedEntities	-7135000	USD
CY2011Q4	eqr	Defined Benefit Plan Expected Future Benefit Payments DefinedBenefitPlanExpectedFutureBenefitPayments	15733000	USD
CY2011Q4	eqr	Defined Benefit Plan Expected Future Benefit Payments Thereafter DefinedBenefitPlanExpectedFutureBenefitPaymentsThereafter	7472000	USD
CY2011	eqr	Defined Contribution Plan Vesting Period DefinedContributionPlanVestingPeriod	5
CY2011	eqr	Dilutive Op Units DilutiveOpUnits	13206000	shares
CY2011	eqr	Dilutive Securities Options DilutiveSecuritiesOptions	4003000	shares
CY2009	eqr	Discontinuation Of Cash Flow Hedge Number Of Contract DiscontinuationOfCashFlowHedgeNumberOfContract	6
CY2011	eqr	Discontinued Operation Corporate Housing Business Gain Loss On Disposal Of Discontinued Operation Net Of Tax DiscontinuedOperationCorporateHousingBusinessGainLossOnDisposalOfDiscontinuedOperationNetOfTax	1200000	USD
CY2011	eqr	Disposal Group Corporate Housing Business Sale DisposalGroupCorporateHousingBusinessSale	4000000	USD
CY2010	eqr	Disposal Group Including Discontinued Operation Amortization Of Deferred Financing Costs DisposalGroupIncludingDiscontinuedOperationAmortizationOfDeferredFinancingCosts	292000	USD
CY2009	eqr	Disposal Group Including Discontinued Operation Amortization Of Deferred Financing Costs DisposalGroupIncludingDiscontinuedOperationAmortizationOfDeferredFinancingCosts	800000	USD
CY2011	eqr	Disposal Group Including Discontinued Operation Amortization Of Deferred Financing Costs DisposalGroupIncludingDiscontinuedOperationAmortizationOfDeferredFinancingCosts	840000	USD
CY2011	eqr	Disposal Group Including Discontinued Operation Depreciation DisposalGroupIncludingDiscontinuedOperationDepreciation	21201000	USD
CY2010	eqr	Disposal Group Including Discontinued Operation Depreciation DisposalGroupIncludingDiscontinuedOperationDepreciation	64791000	USD
CY2009	eqr	Disposal Group Including Discontinued Operation Depreciation DisposalGroupIncludingDiscontinuedOperationDepreciation	86175000	USD
CY2009	eqr	Disposal Group Including Discontinued Operation General And Administrative DisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrative	43000	USD
CY2010	eqr	Disposal Group Including Discontinued Operation General And Administrative DisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrative	42000	USD
CY2011	eqr	Disposal Group Including Discontinued Operation General And Administrative DisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrative	53000	USD
CY2011	eqr	Disposal Group Including Discontinued Operation Interest And Other Income DisposalGroupIncludingDiscontinuedOperationInterestAndOtherIncome	184000	USD
CY2009	eqr	Disposal Group Including Discontinued Operation Interest And Other Income DisposalGroupIncludingDiscontinuedOperationInterestAndOtherIncome	127000	USD
CY2010	eqr	Disposal Group Including Discontinued Operation Interest And Other Income DisposalGroupIncludingDiscontinuedOperationInterestAndOtherIncome	800000	USD
CY2010Q4	eqr	Disposal Group Including Discontinued Operation Mortgage Notes Payable DisposalGroupIncludingDiscontinuedOperationMortgageNotesPayable	104358305.87	USD
CY2011Q4	eqr	Disposal Group Including Discontinued Operation Mortgage Notes Payable DisposalGroupIncludingDiscontinuedOperationMortgageNotesPayable	0	USD
CY2010	eqr	Disposal Group Including Discontinued Operation Other Expenses DisposalGroupIncludingDiscontinuedOperationOtherExpenses	0	USD
CY2009	eqr	Disposal Group Including Discontinued Operation Other Expenses DisposalGroupIncludingDiscontinuedOperationOtherExpenses	11000	USD
CY2011	eqr	Disposal Group Including Discontinued Operation Other Expenses DisposalGroupIncludingDiscontinuedOperationOtherExpenses	0	USD
CY2009	eqr	Disposal Group Including Discontinued Operation Property And Maintenance DisposalGroupIncludingDiscontinuedOperationPropertyAndMaintenance	148449000	USD
CY2010	eqr	Disposal Group Including Discontinued Operation Property And Maintenance DisposalGroupIncludingDiscontinuedOperationPropertyAndMaintenance	119720000	USD
CY2011	eqr	Disposal Group Including Discontinued Operation Property And Maintenance DisposalGroupIncludingDiscontinuedOperationPropertyAndMaintenance	52462000	USD
CY2010	eqr	Disposal Group Including Discontinued Operation Real Estate Taxes And Insurance DisposalGroupIncludingDiscontinuedOperationRealEstateTaxesAndInsurance	25904000	USD
CY2011	eqr	Disposal Group Including Discontinued Operation Real Estate Taxes And Insurance DisposalGroupIncludingDiscontinuedOperationRealEstateTaxesAndInsurance	8836000	USD
CY2009	eqr	Disposal Group Including Discontinued Operation Real Estate Taxes And Insurance DisposalGroupIncludingDiscontinuedOperationRealEstateTaxesAndInsurance	37229000	USD
CY2009	eqr	Disposal Group Including Discontinued Operation Rental Revenue DisposalGroupIncludingDiscontinuedOperationRentalRevenue	395719000	USD
CY2010	eqr	Disposal Group Including Discontinued Operation Rental Revenue DisposalGroupIncludingDiscontinuedOperationRentalRevenue	308945000	USD
CY2011	eqr	Disposal Group Including Discontinued Operation Rental Revenue DisposalGroupIncludingDiscontinuedOperationRentalRevenue	116350000	USD
CY2011	eqr	Disposed Properties DisposedProperties	47
CY2010	eqr	Disposed Properties DisposedProperties	63
CY2011	eqr	Disposed Units DisposedUnits	14345
CY2010	eqr	Disposed Units DisposedUnits	13448
CY2011	eqr	Distributions Minority Interest Partially Owned Properties DistributionsMinorityInterestPartiallyOwnedProperties	1115000	USD
CY2010	eqr	Distributions Minority Interest Partially Owned Properties DistributionsMinorityInterestPartiallyOwnedProperties	2918000	USD
CY2009	eqr	Distributions Minority Interest Partially Owned Properties DistributionsMinorityInterestPartiallyOwnedProperties	2423000	USD
CY2011	eqr	Distributions Preference Interests And Units DistributionsPreferenceInterestsAndUnits	0	USD
CY2010	eqr	Distributions Preference Interests And Units DistributionsPreferenceInterestsAndUnits	0	USD
CY2009	eqr	Distributions Preference Interests And Units DistributionsPreferenceInterestsAndUnits	12000	USD
CY2009	eqr	Dividend Preference Units DividendPreferenceUnits	14479000	USD
CY2011	eqr	Dividend Preference Units DividendPreferenceUnits	13865000	USD
CY2010	eqr	Dividend Preference Units DividendPreferenceUnits	14368000	USD
CY2011Q4	eqr	Earnest Money On Acquisitions EarnestMoneyOnAcquisitions	7882000	USD
CY2010Q4	eqr	Earnest Money On Acquisitions EarnestMoneyOnAcquisitions	9264000	USD
CY2011	eqr	Effect Of Change In Accounting Principle On Earnings Net Of Tax EffectOfChangeInAccountingPrincipleOnEarningsNetOfTax	5000000	USD
CY2010	eqr	Effect Of Change In Accounting Principle On Earnings Net Of Tax EffectOfChangeInAccountingPrincipleOnEarningsNetOfTax	7800000	USD
CY2009	eqr	Effect Of Change In Accounting Principle On Earnings Net Of Tax EffectOfChangeInAccountingPrincipleOnEarningsNetOfTax	10600000	USD
CY2010	eqr	Effect Of Change In Accounting Principle On Earnings Per Share EffectOfChangeInAccountingPrincipleOnEarningsPerShare	0.03
CY2011	eqr	Effect Of Change In Accounting Principle On Earnings Per Share EffectOfChangeInAccountingPrincipleOnEarningsPerShare	0.02
CY2009	eqr	Effect Of Change In Accounting Principle On Earnings Per Share EffectOfChangeInAccountingPrincipleOnEarningsPerShare	0.04
CY2011Q4	eqr	Employee Share Purchase Plan Issuance Price Maximum EmployeeSharePurchasePlanIssuancePriceMaximum	51.19
CY2010Q4	eqr	Employee Share Purchase Plan Issuance Price Maximum EmployeeSharePurchasePlanIssuancePriceMaximum	41.16
CY2009Q4	eqr	Employee Share Purchase Plan Issuance Price Maximum EmployeeSharePurchasePlanIssuancePriceMaximum	24.84
CY2009Q4	eqr	Employee Share Purchase Plan Issuance Price Minimum EmployeeSharePurchasePlanIssuancePriceMinimum	14.21
CY2010Q4	eqr	Employee Share Purchase Plan Issuance Price Minimum EmployeeSharePurchasePlanIssuancePriceMinimum	28.26
CY2011Q4	eqr	Employee Share Purchase Plan Issuance Price Minimum EmployeeSharePurchasePlanIssuancePriceMinimum	44.04
CY2011Q4	eqr	Equity Method Investment Remaining Funding Obligation EquityMethodInvestmentRemainingFundingObligation	5400000	USD
CY2011Q4	eqr	Escrow Deposits For Mortgage And Replacement Reserves EscrowDepositsForMortgageAndReplacementReserves	10692000	USD
CY2010Q4	eqr	Escrow Deposits For Mortgage And Replacement Reserves EscrowDepositsForMortgageAndReplacementReserves	12593000	USD
CY2011	eqr	Estimated Completion Period Of Project EstimatedCompletionPeriodOfProject	September 30, 2013
CY2011	eqr	Estimates Of Lost Revenue And Garage Reconstruction EstimatesOfLostRevenueAndGarageReconstruction	23000000	USD
CY2010	eqr	Expenses Related To Garage Collapse ExpensesRelatedToGarageCollapse	5500000	USD
CY2011	eqr	Expenses Related To Garage Collapse ExpensesRelatedToGarageCollapse	1688597	USD
CY2010Q4	eqr	Fair Value Of Serp Investments FairValueOfSerpInvestments	58132000	USD
CY2011Q4	eqr	Fair Value Of Serp Investments FairValueOfSerpInvestments	71426000	USD
CY2011	eqr	Gain Loss On Debt Extinguishment Notes Net GainLossOnDebtExtinguishmentNotesNet	0	USD
CY2009	eqr	Gain Loss On Debt Extinguishment Notes Net GainLossOnDebtExtinguishmentNotesNet	19925000	USD
CY2010	eqr	Gain Loss On Debt Extinguishment Notes Net GainLossOnDebtExtinguishmentNotesNet	0	USD
CY2011	eqr	Gain Loss On Debt Extinguishments Mortgage Notes Payable GainLossOnDebtExtinguishmentsMortgageNotesPayable	0	USD
CY2010	eqr	Gain Loss On Debt Extinguishments Mortgage Notes Payable GainLossOnDebtExtinguishmentsMortgageNotesPayable	-2457000	USD
CY2009	eqr	Gain Loss On Debt Extinguishments Mortgage Notes Payable GainLossOnDebtExtinguishmentsMortgageNotesPayable	2400000	USD
CY2011	eqr	Gain Loss On Sale Of Land Parcels GainLossOnSaleOfLandParcels	4217000	USD
CY2009	eqr	Gain Loss On Sale Of Land Parcels GainLossOnSaleOfLandParcels	0	USD
CY2010	eqr	Gain Loss On Sale Of Land Parcels GainLossOnSaleOfLandParcels	-1395000	USD
CY2010	eqr	Gain Loss On Sales Of Land Parcels GainLossOnSalesOfLandParcels	-1395000	USD
CY2009	eqr	Gain Loss On Sales Of Land Parcels GainLossOnSalesOfLandParcels	0	USD
CY2011	eqr	Gain Loss On Sales Of Land Parcels GainLossOnSalesOfLandParcels	4217000	USD
CY2010Q4	eqr	Historical Cost Of Encumbered Properties HistoricalCostOfEncumberedProperties	5600000000	USD
CY2011Q4	eqr	Historical Cost Of Encumbered Properties HistoricalCostOfEncumberedProperties	4900000000	USD
CY2011	eqr	Historical Volatility Period Basis HistoricalVolatilityPeriodBasis	10
CY2011	eqr	Income From Continuing Operations Available To Common Shares IncomeFromContinuingOperationsAvailableToCommonShares	61746000	USD
CY2009	eqr	Income From Technology Investments IncomeFromTechnologyInvestments	0	USD
CY2010	eqr	Income From Technology Investments IncomeFromTechnologyInvestments	0	USD
CY2011	eqr	Income From Technology Investments IncomeFromTechnologyInvestments	4537000	USD
CY2010Q3	eqr	Income Loss From Continuing Operations Adjusted To Discontinued Operations IncomeLossFromContinuingOperationsAdjustedToDiscontinuedOperations	-1188000	USD
CY2010Q4	eqr	Income Loss From Continuing Operations Adjusted To Discontinued Operations IncomeLossFromContinuingOperationsAdjustedToDiscontinuedOperations	-1305000	USD
CY2010Q1	eqr	Income Loss From Continuing Operations Adjusted To Discontinued Operations IncomeLossFromContinuingOperationsAdjustedToDiscontinuedOperations	-1066000	USD
CY2010Q2	eqr	Income Loss From Continuing Operations Adjusted To Discontinued Operations IncomeLossFromContinuingOperationsAdjustedToDiscontinuedOperations	-1314000	USD
CY2011Q1	eqr	Income Loss From Continuing Operations Adjusted To Discontinued Operations IncomeLossFromContinuingOperationsAdjustedToDiscontinuedOperations	-1344000	USD
CY2011Q4	eqr	Income Loss From Continuing Operations Adjusted To Discontinued Operations IncomeLossFromContinuingOperationsAdjustedToDiscontinuedOperations	-2195000	USD
CY2011Q2	eqr	Income Loss From Continuing Operations Adjusted To Discontinued Operations IncomeLossFromContinuingOperationsAdjustedToDiscontinuedOperations	-1887000	USD
CY2011Q3	eqr	Income Loss From Continuing Operations Adjusted To Discontinued Operations IncomeLossFromContinuingOperationsAdjustedToDiscontinuedOperations	-2129000	USD
CY2010Q3	eqr	Income Loss From Continuing Operations Adjusted To Discountinued Operations IncomeLossFromContinuingOperationsAdjustedToDiscountinuedOperations	1188000	USD
CY2010Q2	eqr	Income Loss From Continuing Operations Adjusted To Discountinued Operations IncomeLossFromContinuingOperationsAdjustedToDiscountinuedOperations	1314000	USD
CY2010Q1	eqr	Income Loss From Continuing Operations Adjusted To Discountinued Operations IncomeLossFromContinuingOperationsAdjustedToDiscountinuedOperations	1066000	USD
CY2010Q4	eqr	Income Loss From Continuing Operations Adjusted To Discountinued Operations IncomeLossFromContinuingOperationsAdjustedToDiscountinuedOperations	1305000	USD
CY2011Q3	eqr	Income Loss From Continuing Operations Adjusted To Discountinued Operations IncomeLossFromContinuingOperationsAdjustedToDiscountinuedOperations	2129000	USD
CY2011Q2	eqr	Income Loss From Continuing Operations Adjusted To Discountinued Operations IncomeLossFromContinuingOperationsAdjustedToDiscountinuedOperations	1887000	USD
CY2011Q4	eqr	Income Loss From Continuing Operations Adjusted To Discountinued Operations IncomeLossFromContinuingOperationsAdjustedToDiscountinuedOperations	2195000	USD
CY2011Q1	eqr	Income Loss From Continuing Operations Adjusted To Discountinued Operations IncomeLossFromContinuingOperationsAdjustedToDiscountinuedOperations	1344000	USD
CY2009	eqr	Income Loss From Continuing Operations Available To Units IncomeLossFromContinuingOperationsAvailableToUnits	-77150000	USD
CY2011	eqr	Income Loss From Continuing Operations Available To Units IncomeLossFromContinuingOperationsAvailableToUnits	61746000	USD
CY2010	eqr	Income Loss From Continuing Operations Available To Units IncomeLossFromContinuingOperationsAvailableToUnits	-101941000	USD
CY2009	eqr	Income Loss From Discontinued Operations IncomeLossFromDiscontinuedOperations	109950000	USD
CY2011	eqr	Income Loss From Discontinued Operations IncomeLossFromDiscontinuedOperations	32265000	USD
CY2010	eqr	Income Loss From Discontinued Operations IncomeLossFromDiscontinuedOperations	86326000	USD
CY2012Q1	eqr	Increase To Line Of Credit IncreaseToLineOfCredit	500000000	USD
CY2011Q4	eqr	Indirect Ownership Interest Percentage IndirectOwnershipInterestPercentage	0.01
CY2011	eqr	Initial Insurance Proceeds InitialInsuranceProceeds	6103245	USD
CY2010	eqr	Initial Insurance Proceeds InitialInsuranceProceeds	4000000	USD
CY2010	eqr	Insurance Litigation Expenses InsuranceLitigationExpenses	1700000	USD
CY2009	eqr	Insurance Litigation Settlement Proceeds InsuranceLitigationSettlementProceeds	170704	USD
CY2010	eqr	Insurance Litigation Settlement Proceeds InsuranceLitigationSettlementProceeds	5191920	USD
CY2011	eqr	Insurance Litigation Settlement Proceeds InsuranceLitigationSettlementProceeds	800000	USD
CY2011	eqr	Insurance Reimbursements InsuranceReimbursements	12000000	USD
CY2011	eqr	Interest Capitalized For Real Estate Under Development InterestCapitalizedForRealEstateUnderDevelopment	-8785000	USD
CY2009	eqr	Interest Capitalized For Real Estate Under Development InterestCapitalizedForRealEstateUnderDevelopment	-34859000	USD
CY2010	eqr	Interest Capitalized For Real Estate Under Development InterestCapitalizedForRealEstateUnderDevelopment	-13008000	USD
CY2011	eqr	Interest Capitalized For Unconsolidated Entities Under Development InterestCapitalizedForUnconsolidatedEntitiesUnderDevelopment	-323000	USD
CY2010	eqr	Interest Capitalized For Unconsolidated Entities Under Development InterestCapitalizedForUnconsolidatedEntitiesUnderDevelopment	0	USD
CY2009	eqr	Interest Capitalized For Unconsolidated Entities Under Development InterestCapitalizedForUnconsolidatedEntitiesUnderDevelopment	0	USD
CY2010	eqr	Issuance Of Op Units To Buyout Interest IssuanceOfOpUnitsToBuyoutInterest	1129	shares
CY2009	eqr	Issuance Of Op Units To Buyout Interest IssuanceOfOpUnitsToBuyoutInterest	32061	shares
CY2010	eqr	Issuance Price Op Units To Increase Ownership IssuancePriceOpUnitsToIncreaseOwnership	800000	USD
CY2009	eqr	Issuance Price Op Units To Increase Ownership IssuancePriceOpUnitsToIncreaseOwnership	800000	USD
CY2009	eqr	Issue Price Ltip Unit IssuePriceLtipUnit	0.50
CY2011	eqr	Issue Price Ltip Unit IssuePriceLtipUnit	0
CY2010	eqr	Issue Price Ltip Unit IssuePriceLtipUnit	0
CY2011	eqr	Issue Price Op Unit IssuePriceOpUnit	0
CY2009	eqr	Issue Price Op Unit IssuePriceOpUnit	26.50
CY2010	eqr	Issue Price Op Unit IssuePriceOpUnit	40.09
CY2010	eqr	Issue Price Operating Partnership Unit IssuePriceOperatingPartnershipUnit	8200000	USD
CY2011	eqr	Issue Price Operating Partnership Unit IssuePriceOperatingPartnershipUnit	0	USD
CY2009	eqr	Issue Price Operating Partnership Unit IssuePriceOperatingPartnershipUnit	800000	USD
CY2011Q4	eqr	Joint Venture Partner Ownership Percentage JointVenturePartnerOwnershipPercentage	0.80
CY2010Q4	eqr	Land And Depreciable Property Net LandAndDepreciablePropertyNet	10900000000	USD
CY2011Q4	eqr	Land And Depreciable Property Net LandAndDepreciablePropertyNet	11400000000	USD
CY2010	eqr	Land Parcels Acquired From Outside Partner LandParcelsAcquiredFromOutsidePartner	1
CY2011Q4	eqr	Land Parcels Contracted To Be Acquired LandParcelsContractedToBeAcquired	0
CY2011Q4	eqr	Land Purchase Price LandPurchasePrice	76100000	USD
CY2012Q1	eqr	Landparcelsacquiredsubsequentevents Landparcelsacquiredsubsequentevents	2
CY2010	eqr	Limited Partners Change In Carrying Value LimitedPartnersChangeInCarryingValue	-4658000	USD
CY2011	eqr	Limited Partners Change In Carrying Value LimitedPartnersChangeInCarryingValue	10150000	USD
CY2009	eqr	Limited Partners Change In Carrying Value LimitedPartnersChangeInCarryingValue	-20658000	USD
CY2010	eqr	Limited Partners Change In Redemption Value LimitedPartnersChangeInRedemptionValue	129918000	USD
CY2011	eqr	Limited Partners Change In Redemption Value LimitedPartnersChangeInRedemptionValue	22714000	USD
CY2009	eqr	Limited Partners Change In Redemption Value LimitedPartnersChangeInRedemptionValue	14544000	USD
CY2011	eqr	Loss Contingency Released Reserves LossContingencyReleasedReserves	1100000	USD
CY2011Q4	eqr	Market Value Of Common Shares MarketValueOfCommonShares	57.03
CY2011	eqr	Maximum Eligible Compensation Percentage For Defined Contribution Plan By Employer MaximumEligibleCompensationPercentageForDefinedContributionPlanByEmployer	0.03
CY2011Q4	eqr	Military Housing Properties MilitaryHousingProperties	2
CY2011Q4	eqr	Military Housing Units MilitaryHousingUnits	4901
CY2009	eqr	Minority Interest Change In Carrying Value MinorityInterestChangeInCarryingValue	-20658000	USD
CY2010	eqr	Minority Interest Change In Carrying Value MinorityInterestChangeInCarryingValue	-4658000	USD
CY2011	eqr	Minority Interest Change In Carrying Value MinorityInterestChangeInCarryingValue	10150000	USD
CY2010	eqr	Mortgage Debt Released MortgageDebtReleased	40000000	USD
CY2010	eqr	Mortgage Loans Assumed By Purchaser MortgageLoansAssumedByPurchaser	-39999000	USD
CY2011	eqr	Mortgage Loans Assumed By Purchaser MortgageLoansAssumedByPurchaser	0	USD
CY2009	eqr	Mortgage Loans Assumed By Purchaser MortgageLoansAssumedByPurchaser	-17313000	USD
CY2010	eqr	Mortgage Notes Payable Lump Sum Pay Offs MortgageNotesPayableLumpSumPayOffs	635285000	USD
CY2009	eqr	Mortgage Notes Payable Lump Sum Pay Offs MortgageNotesPayableLumpSumPayOffs	939022000	USD
CY2011	eqr	Mortgage Notes Payable Lump Sum Pay Offs MortgageNotesPayableLumpSumPayOffs	974956000	USD
CY2009	eqr	Net Income Loss Available To Common Stockholder Basic NetIncomeLossAvailableToCommonStockholderBasic	347794000	USD
CY2010	eqr	Net Income Loss Available To Common Stockholder Basic NetIncomeLossAvailableToCommonStockholderBasic	269242000	USD
CY2011	eqr	Net Income Loss Available To Common Stockholder Basic NetIncomeLossAvailableToCommonStockholderBasic	879720000	USD
CY2010	eqr	Net Income Loss Available To Op Unitholders Basic Diluted Numerator NetIncomeLossAvailableToOpUnitholdersBasicDilutedNumerator	282341000	USD
CY2009	eqr	Net Income Loss Available To Op Unitholders Basic Diluted Numerator NetIncomeLossAvailableToOpUnitholdersBasicDilutedNumerator	368099000	USD
CY2011	eqr	Net Income Loss Available To Op Unitholders Basic Diluted Numerator NetIncomeLossAvailableToOpUnitholdersBasicDilutedNumerator	920500000	USD
CY2011Q4	eqr	Noncontrolling Interests Partially Owned Properties NoncontrollingInterestsPartiallyOwnedProperties	74306000	USD
CY2010Q4	eqr	Noncontrolling Interests Partially Owned Properties NoncontrollingInterestsPartiallyOwnedProperties	7991000	USD
CY2011Q4	eqr	Noncontrolling Interests Settlement Value NoncontrollingInterestsSettlementValue	33800000	USD
CY2011Q4	eqr	Number Of Apartments Units Under Development Unconsolidated Projects NumberOfApartmentsUnitsUnderDevelopmentUnconsolidatedProjects	945
CY2012Q1	eqr	Number Of Consolidated Apartment Units Sold NumberOfConsolidatedApartmentUnitsSold	704
CY2012Q1	eqr	Number Of Consolidated Properties Disposed Of NumberOfConsolidatedPropertiesDisposedOf	1
CY2011	eqr	Number Of Installments For Vesting Of Stock Option NumberOfInstallmentsForVestingOfStockOption	three equal installments
CY2011Q4	eqr	Number Of Joint Venture Loans NumberOfJointVentureLoans	2
CY2011Q4	eqr	Number Of Joint Ventures NumberOfJointVentures	2
CY2011Q4	eqr	Number Of Land Parcels Under Long Term Ground Leases NumberOfLandParcelsUnderLongTermGroundLeases	1
CY2011Q4	eqr	Number Of Operating Properties And Land Parcels Under Long Term Ground Leases NumberOfOperatingPropertiesAndLandParcelsUnderLongTermGroundLeases	5
CY2011Q4	eqr	Number Of Operating Properties Under Long Term Ground Leases NumberOfOperatingPropertiesUnderLongTermGroundLeases	4
CY2010	eqr	Number Of Potential Condo Sales NumberOfPotentialCondoSales	38
CY2011Q4	eqr	Number Of Projects In Various Stages Of Development NumberOfProjectsInVariousStagesOfDevelopment	6
CY2011Q4	eqr	Number Of Properties Encumbered NumberOfPropertiesEncumbered	47
CY2011Q4	eqr	Number Of Shares Available For Issuance NumberOfSharesAvailableForIssuance	4849796	shares
CY2011Q4	eqr	Number Of Unconsolidated Projects NumberOfUnconsolidatedProjects	2
CY2009Q4	eqr	Number Of Units In Same Store Properties NumberOfUnitsInSameStoreProperties	112042
CY2010Q4	eqr	Number Of Units In Same Store Properties NumberOfUnitsInSameStoreProperties	101312
CY2011Q4	eqr	Number Of Units In Same Store Properties NumberOfUnitsInSameStoreProperties	101312
CY2011Q4	eqr	Number Of Units In Various Stages Of Development NumberOfUnitsInVariousStagesOfDevelopment	1535
CY2010Q3	eqr	Operating Income Loss Adjusted To Discountinued Operations OperatingIncomeLossAdjustedToDiscountinuedOperations	-1813000	USD
CY2010Q4	eqr	Operating Income Loss Adjusted To Discountinued Operations OperatingIncomeLossAdjustedToDiscountinuedOperations	-1925000	USD
CY2010Q2	eqr	Operating Income Loss Adjusted To Discountinued Operations OperatingIncomeLossAdjustedToDiscountinuedOperations	-1946000	USD
CY2010Q1	eqr	Operating Income Loss Adjusted To Discountinued Operations OperatingIncomeLossAdjustedToDiscountinuedOperations	-1703000	USD
CY2011Q3	eqr	Operating Income Loss Adjusted To Discountinued Operations OperatingIncomeLossAdjustedToDiscountinuedOperations	-2129000	USD
CY2011Q1	eqr	Operating Income Loss Adjusted To Discountinued Operations OperatingIncomeLossAdjustedToDiscountinuedOperations	-1957000	USD
CY2011Q2	eqr	Operating Income Loss Adjusted To Discountinued Operations OperatingIncomeLossAdjustedToDiscountinuedOperations	-2191000	USD
CY2011Q4	eqr	Operating Income Loss Adjusted To Discountinued Operations OperatingIncomeLossAdjustedToDiscountinuedOperations	-2195000	USD
CY2010	eqr	Other Comprehensive Income Loss OtherComprehensiveIncomeLoss	-62499000	USD
CY2009	eqr	Other Comprehensive Income Loss OtherComprehensiveIncomeLoss	40480000	USD
CY2011	eqr	Other Comprehensive Income Loss OtherComprehensiveIncomeLoss	-138900000	USD
CY2010Q4	eqr	Other Restricted Cash OtherRestrictedCash	8125000	USD
CY2011Q4	eqr	Other Restricted Cash OtherRestrictedCash	3944000	USD
CY2009	eqr	Overhead Costs OverheadCosts	1400000	USD
CY2011	eqr	Overhead Costs OverheadCosts	400000	USD
CY2010	eqr	Overhead Costs OverheadCosts	600000	USD
CY2011Q4	eqr	Partially Owned Consolidated Properties PartiallyOwnedConsolidatedProperties	21
CY2011Q4	eqr	Partially Owned Consolidated Units PartiallyOwnedConsolidatedUnits	3916
CY2010	eqr	Partially Owned Development Projects Acquired From Outside Partner PartiallyOwnedDevelopmentProjectsAcquiredFromOutsidePartner	1
CY2011Q4	eqr	Partially Owned Limited Life Partnership Properties PartiallyOwnedLimitedLifePartnershipProperties	6
CY2009	eqr	Partially Owned Properties Acquired Properties PartiallyOwnedPropertiesAcquiredProperties	5
CY2011	eqr	Partially Owned Properties Acquired Properties PartiallyOwnedPropertiesAcquiredProperties	3
CY2010	eqr	Partially Owned Properties Acquired Properties PartiallyOwnedPropertiesAcquiredProperties	2
CY2009	eqr	Partially Owned Properties Increase In Ownership Number Of Properties PartiallyOwnedPropertiesIncreaseInOwnershipNumberOfProperties	2
CY2010	eqr	Partially Owned Properties Increase In Ownership Number Of Properties PartiallyOwnedPropertiesIncreaseInOwnershipNumberOfProperties	3
CY2009	eqr	Partially Owned Units Acquired Units PartiallyOwnedUnitsAcquiredUnits	1587
CY2010	eqr	Partially Owned Units Acquired Units PartiallyOwnedUnitsAcquiredUnits	432
CY2011	eqr	Partially Owned Units Acquired Units PartiallyOwnedUnitsAcquiredUnits	1351
	eqr	Partners Payments To Acquire Equity Method Investments PartnersPaymentsToAcquireEquityMethodInvestments	40100000	USD
CY2011	eqr	Payments To Acquire Other Capital Assets PaymentsToAcquireOtherCapitalAssets	7110000	USD
CY2009	eqr	Payments To Acquire Other Capital Assets PaymentsToAcquireOtherCapitalAssets	2028000	USD
CY2010	eqr	Payments To Acquire Other Capital Assets PaymentsToAcquireOtherCapitalAssets	2991000	USD
CY2011Q4	eqr	Preferred Units Value Outstanding PreferredUnitsValueOutstanding	200000000	USD
CY2010Q4	eqr	Preferred Units Value Outstanding PreferredUnitsValueOutstanding	200000000	USD
CY2010	eqr	Prepayment Penalty Charges PrepaymentPenaltyCharges	2500000	USD
CY2010	eqr	Price Per Unit Issued PricePerUnitIssued	39.15
CY2010	eqr	Proceeds From Distributions Received From Unconsolidated Subsidiaries ProceedsFromDistributionsReceivedFromUnconsolidatedSubsidiaries	26924000	USD
CY2011	eqr	Proceeds From Distributions Received From Unconsolidated Subsidiaries ProceedsFromDistributionsReceivedFromUnconsolidatedSubsidiaries	0	USD
CY2009	eqr	Proceeds From Distributions Received From Unconsolidated Subsidiaries ProceedsFromDistributionsReceivedFromUnconsolidatedSubsidiaries	6521000	USD
CY2010	eqr	Proceeds From Payments On Settlement Of Derivative Instruments Other Assets ProceedsFromPaymentsOnSettlementOfDerivativeInstrumentsOtherAssets	0	USD
CY2011	eqr	Proceeds From Payments On Settlement Of Derivative Instruments Other Assets ProceedsFromPaymentsOnSettlementOfDerivativeInstrumentsOtherAssets	0	USD
CY2009	eqr	Proceeds From Payments On Settlement Of Derivative Instruments Other Assets ProceedsFromPaymentsOnSettlementOfDerivativeInstrumentsOtherAssets	11253000	USD
CY2009	eqr	Proceeds From Payments On Settlement Of Derivative Instruments Other Liabilities ProceedsFromPaymentsOnSettlementOfDerivativeInstrumentsOtherLiabilities	0	USD
CY2010	eqr	Proceeds From Payments On Settlement Of Derivative Instruments Other Liabilities ProceedsFromPaymentsOnSettlementOfDerivativeInstrumentsOtherLiabilities	-10040000	USD
CY2011	eqr	Proceeds From Payments On Settlement Of Derivative Instruments Other Liabilities ProceedsFromPaymentsOnSettlementOfDerivativeInstrumentsOtherLiabilities	-147306000	USD
CY2011	eqr	Proceeds From Royalty Termination ProceedsFromRoyaltyTermination	4500000	USD
CY2011	eqr	Proceeds From Sale Of Equity Interest ProceedsFromSaleOfEquityInterest	-28360000	USD
CY2010	eqr	Proceeds From Sale Of Equity Interest ProceedsFromSaleOfEquityInterest	-11708000	USD
CY2009	eqr	Proceeds From Sale Of Equity Interest ProceedsFromSaleOfEquityInterest	0	USD
CY2011	eqr	Proceeds From Sale Of Property ProceedsFromSaleOfProperty	1505025000	USD
CY2010	eqr	Proceeds From Sale Of Property ProceedsFromSaleOfProperty	1140491000	USD
CY2009	eqr	Proceeds From Technology Investments ProceedsFromTechnologyInvestments	0	USD
CY2011	eqr	Proceeds From Technology Investments ProceedsFromTechnologyInvestments	4537000	USD
CY2010	eqr	Proceeds From Technology Investments ProceedsFromTechnologyInvestments	0	USD
CY2009	eqr	Proceeds From Unsecured Line Of Credit ProceedsFromUnsecuredLineOfCredit	0	USD
CY2010	eqr	Proceeds From Unsecured Line Of Credit ProceedsFromUnsecuredLineOfCredit	5513125000	USD
CY2012Q1	eqr	Proceeds Received From Seller Provided Finanacing ProceedsReceivedFromSellerProvidedFinanacing	200000	USD
CY2011Q4	eqr	Project Cost ProjectCost	232800000	USD
CY2010	eqr	Properties Acquired PropertiesAcquired	16
CY2011	eqr	Proceeds From Unsecured Line Of Credit ProceedsFromUnsecuredLineOfCredit	1455000000	USD
CY2011	eqr	Properties Acquired PropertiesAcquired	21
CY2011Q4	eqr	Properties Contracted To Be Acquired PropertiesContractedToBeAcquired	2
CY2011Q4	eqr	Properties Contracted To Be Disposed PropertiesContractedToBeDisposed	6
CY2011	eqr	Properties Designed And Built In Violation Of Accessibility Requirements PropertiesDesignedAndBuiltInViolationOfAccessibilityRequirements	300
CY2010	eqr	Properties Disposed PropertiesDisposed	2
CY2011Q4	eqr	Properties Having Fee Simple Title PropertiesHavingFeeSimpleTitle	400
CY2011Q4	eqr	Properties Having Less Than Hundred Percent Fee Simple Title PropertiesHavingLessThanHundredPercentFeeSimpleTitle	1
CY2010	eqr	Property Units Acquired PropertyUnitsAcquired	4445
CY2011	eqr	Property Units Acquired PropertyUnitsAcquired	6198
CY2011	eqr	Provision For Income Franchise And Excise Taxes ProvisionForIncomeFranchiseAndExciseTaxes	485000	USD
CY2009	eqr	Provision For Income Franchise And Excise Taxes ProvisionForIncomeFranchiseAndExciseTaxes	1643000	USD
CY2010	eqr	Provision For Income Franchise And Excise Taxes ProvisionForIncomeFranchiseAndExciseTaxes	378000	USD
CY2011Q4	eqr	Purchase Price For Commitments To Acquire PurchasePriceForCommitmentsToAcquire	294200000	USD
CY2010	eqr	Real Estate Accumulated Depreciation Dispositions And Other RealEstateAccumulatedDepreciationDispositionsAndOther	-213610000	USD
CY2011	eqr	Real Estate Accumulated Depreciation Dispositions And Other RealEstateAccumulatedDepreciationDispositionsAndOther	-461390000	USD
CY2009	eqr	Real Estate Accumulated Depreciation Dispositions And Other RealEstateAccumulatedDepreciationDispositionsAndOther	-284111000	USD
CY2010	eqr	Real Estate Acquisitions And Development RealEstateAcquisitionsAndDevelopment	1789948000	USD
CY2009	eqr	Real Estate Acquisitions And Development RealEstateAcquisitionsAndDevelopment	512977000	USD
CY2011	eqr	Real Estate Acquisitions And Development RealEstateAcquisitionsAndDevelopment	1721895000	USD
CY2011	eqr	Real Estate And Accumulated Depreciation Description Of Location RealEstateAndAccumulatedDepreciationDescriptionOfLocation	Corona, CA
CY2010	eqr	Real Estate Dispositions And Other RealEstateDispositionsAndOther	-693920000	USD
CY2009	eqr	Real Estate Dispositions And Other RealEstateDispositionsAndOther	-864037000	USD
CY2011	eqr	Real Estate Dispositions And Other RealEstateDispositionsAndOther	-1167796000	USD
CY2010Q4	eqr	Receivable For Common Shares Issued ReceivableForCommonSharesIssued	37550000	USD
CY2011Q4	eqr	Receivable For Common Shares Issued ReceivableForCommonSharesIssued	0	USD
CY2009Q4	eqr	Receivable For Common Shares Issued ReceivableForCommonSharesIssued	0	USD
CY2010Q4	eqr	Redeemable Noncontrolling Interest Operating Partnership Fair Value Disclosure RedeemableNoncontrollingInterestOperatingPartnershipFairValueDisclosure	383540000	USD
CY2011Q4	eqr	Redeemable Noncontrolling Interest Operating Partnership Fair Value Disclosure RedeemableNoncontrollingInterestOperatingPartnershipFairValueDisclosure	416404000	USD
CY2011Q4	eqr	Redeemable Noncontrolling Interests Operating Partnership RedeemableNoncontrollingInterestsOperatingPartnership	416404000	USD
CY2010Q4	eqr	Redeemable Noncontrolling Interests Operating Partnership RedeemableNoncontrollingInterestsOperatingPartnership	383540000	USD
CY2009Q4	eqr	Redemption Value Limited Partners RedemptionValueLimitedPartners	258280000	USD
CY2010Q4	eqr	Redemption Value Limited Partners RedemptionValueLimitedPartners	383540000	USD
CY2008Q4	eqr	Redemption Value Limited Partners RedemptionValueLimitedPartners	264394000	USD
CY2011Q4	eqr	Redemption Value Limited Partners RedemptionValueLimitedPartners	416404000	USD
CY2009Q4	eqr	Redemption Value Non Controlling Interests RedemptionValueNonControllingInterests	258280000	USD
CY2011Q4	eqr	Redemption Value Non Controlling Interests RedemptionValueNonControllingInterests	416404000	USD
CY2010Q4	eqr	Redemption Value Non Controlling Interests RedemptionValueNonControllingInterests	383540000	USD
CY2008Q4	eqr	Redemption Value Non Controlling Interests RedemptionValueNonControllingInterests	264394000	USD
CY2010	eqr	Reduction In Other Liabilities ReductionInOtherLiabilities	200000	USD
CY2011	eqr	Reduction In Partially Owned Properties ReductionInPartiallyOwnedProperties	8000000	USD
CY2009	eqr	Reduction In Partially Owned Properties ReductionInPartiallyOwnedProperties	11700000	USD
CY2010	eqr	Reduction In Partially Owned Properties ReductionInPartiallyOwnedProperties	200000	USD
CY2011	eqr	Reduction Of Paid In Capital ReductionOfPaidInCapital	4800000	USD
CY2010	eqr	Reduction Of Paid In Capital ReductionOfPaidInCapital	16900000	USD
CY2009	eqr	Reduction Of Paid In Capital ReductionOfPaidInCapital	1500000	USD
CY2012Q1	eqr	Remaining Acquisition Cost Contracted RemainingAcquisitionCostContracted	1485000000	USD
CY2012Q1	eqr	Remaining Ownership Percentage Contracted RemainingOwnershipPercentageContracted	0.265
CY2011	eqr	Repayments Of Mortgage Notes Payable RepaymentsOfMortgageNotesPayable	16726000	USD
CY2009	eqr	Repayments Of Mortgage Notes Payable RepaymentsOfMortgageNotesPayable	17763000	USD
CY2010	eqr	Repayments Of Mortgage Notes Payable RepaymentsOfMortgageNotesPayable	16769000	USD
CY2010Q4	eqr	Resident Security And Utility Deposits ResidentSecurityAndUtilityDeposits	40745000	USD
CY2011Q4	eqr	Resident Security And Utility Deposits ResidentSecurityAndUtilityDeposits	40403000	USD
CY2010Q4	eqr	Restricted Deposits On Debt RestrictedDepositsOnDebt	18966000	USD
CY2009	eqr	Segment Reporting Information Non Same Store Net Operating Income SegmentReportingInformationNonSameStoreNetOperatingIncome	21336000	USD
CY2010	eqr	Segment Reporting Information Non Same Store Net Operating Income SegmentReportingInformationNonSameStoreNetOperatingIncome	53734000	USD
CY2011	eqr	Segment Reporting Information Non Same Store Net Operating Income SegmentReportingInformationNonSameStoreNetOperatingIncome	164438000	USD
CY2011Q4	eqr	Restricted Deposits On Debt RestrictedDepositsOnDebt	2370000	USD
CY2010Q4	eqr	Restricted Deposits On Real Estate Investments RestrictedDepositsOnRealEstateInvestments	0	USD
CY2011Q4	eqr	Restricted Deposits On Real Estate Investments RestrictedDepositsOnRealEstateInvestments	43970000	USD
CY2011	eqr	Restricted Share Grants Net RestrictedShareGrantsNet	145616	shares
CY2009	eqr	Restricted Share Grants Net RestrictedShareGrantsNet	298717	shares
CY2010	eqr	Restricted Share Grants Net RestrictedShareGrantsNet	235767	shares
CY2008Q4	eqr	Retained Earnings Decrease RetainedEarningsDecrease	27000000	USD
CY2011Q4	eqr	Sales Price For Commitments To Dispose SalesPriceForCommitmentsToDispose	127075000	USD
CY2010Q4	eqr	Sales Revenue Net Adjusted To Discontinued Operations SalesRevenueNetAdjustedToDiscontinuedOperations	-4781000	USD
CY2010Q3	eqr	Sales Revenue Net Adjusted To Discontinued Operations SalesRevenueNetAdjustedToDiscontinuedOperations	-4811000	USD
CY2010Q2	eqr	Sales Revenue Net Adjusted To Discontinued Operations SalesRevenueNetAdjustedToDiscontinuedOperations	-4759000	USD
CY2010Q1	eqr	Sales Revenue Net Adjusted To Discontinued Operations SalesRevenueNetAdjustedToDiscontinuedOperations	-4673000	USD
CY2011Q4	eqr	Sales Revenue Net Adjusted To Discontinued Operations SalesRevenueNetAdjustedToDiscontinuedOperations	-5130000	USD
CY2011Q3	eqr	Sales Revenue Net Adjusted To Discontinued Operations SalesRevenueNetAdjustedToDiscontinuedOperations	-5127000	USD
CY2011Q2	eqr	Sales Revenue Net Adjusted To Discontinued Operations SalesRevenueNetAdjustedToDiscontinuedOperations	-5063000	USD
CY2011Q1	eqr	Sales Revenue Net Adjusted To Discontinued Operations SalesRevenueNetAdjustedToDiscontinuedOperations	-4874000	USD
CY2011Q4	eqr	Secured Debt Instrument Fair Value SecuredDebtInstrumentFairValue	4300000000	USD
CY2010Q4	eqr	Secured Debt Instrument Fair Value SecuredDebtInstrumentFairValue	4700000000	USD
CY2009	eqr	Segment Reporting Information Net Operating Income SegmentReportingInformationNetOperatingIncome	985826000	USD
CY2010	eqr	Segment Reporting Information Net Operating Income SegmentReportingInformationNetOperatingIncome	1058085000	USD
CY2011	eqr	Segment Reporting Information Net Operating Income SegmentReportingInformationNetOperatingIncome	1246134000	USD
CY2009	eqr	Segment Reporting Information Same Store Net Operating Income SegmentReportingInformationSameStoreNetOperatingIncome	1081827000	USD
CY2010	eqr	Segment Reporting Information Same Store Net Operating Income SegmentReportingInformationSameStoreNetOperatingIncome	1016272000	USD
CY2011	eqr	Segment Reporting Information Same Store Net Operating Income SegmentReportingInformationSameStoreNetOperatingIncome	1094716000	USD
CY2009	eqr	Segment Reporting Segment Non Same Store Operating Expenses SegmentReportingSegmentNonSameStoreOperatingExpenses	94486000	USD
CY2010	eqr	Segment Reporting Segment Non Same Store Operating Expenses SegmentReportingSegmentNonSameStoreOperatingExpenses	79576000	USD
CY2011	eqr	Segment Reporting Segment Non Same Store Operating Expenses SegmentReportingSegmentNonSameStoreOperatingExpenses	103571000	USD
CY2009	eqr	Segment Reporting Segment Non Same Store Rental Income SegmentReportingSegmentNonSameStoreRentalIncome	115822000	USD
CY2010	eqr	Segment Reporting Segment Non Same Store Rental Income SegmentReportingSegmentNonSameStoreRentalIncome	133310000	USD
CY2011	eqr	Segment Reporting Segment Non Same Store Rental Income SegmentReportingSegmentNonSameStoreRentalIncome	268009000	USD
CY2009	eqr	Segment Reporting Segment Operating Expenses SegmentReportingSegmentOperatingExpenses	624643000	USD
CY2010	eqr	Segment Reporting Segment Operating Expenses SegmentReportingSegmentOperatingExpenses	686683000	USD
CY2011	eqr	Segment Reporting Segment Operating Expenses SegmentReportingSegmentOperatingExpenses	714109000	USD
CY2009	eqr	Segment Reporting Segment Properties Sold Net Operating Income SegmentReportingSegmentPropertiesSoldNetOperatingIncome	-104690000	USD
CY2009	eqr	Segment Reporting Segment Properties Sold Operating Expenses SegmentReportingSegmentPropertiesSoldOperatingExpenses	-111589000	USD
CY2009	eqr	Segment Reporting Segment Properties Sold Rental Income SegmentReportingSegmentPropertiesSoldRentalIncome	-216279000	USD
CY2009	eqr	Segment Reporting Segment Same Store Operating Expenses SegmentReportingSegmentSameStoreOperatingExpenses	648508000	USD
CY2010	eqr	Segment Reporting Segment Same Store Operating Expenses SegmentReportingSegmentSameStoreOperatingExpenses	614210000	USD
CY2011	eqr	Segment Reporting Segment Same Store Operating Expenses SegmentReportingSegmentSameStoreOperatingExpenses	617712000	USD
CY2009	eqr	Segment Reporting Segment Same Store Rental Income SegmentReportingSegmentSameStoreRentalIncome	1730335000	USD
CY2010	eqr	Segment Reporting Segment Same Store Rental Income SegmentReportingSegmentSameStoreRentalIncome	1630482000	USD
CY2011	eqr	Segment Reporting Segment Same Store Rental Income SegmentReportingSegmentSameStoreRentalIncome	1712428000	USD
CY2009	eqr	Segmentreportingsegmentpropertiessoldnetoperatingincomeyeartodate Segmentreportingsegmentpropertiessoldnetoperatingincomeyeartodate	-12647000	USD
CY2010	eqr	Segmentreportingsegmentpropertiessoldnetoperatingincomeyeartodate Segmentreportingsegmentpropertiessoldnetoperatingincomeyeartodate	-11921000	USD
CY2011	eqr	Segmentreportingsegmentpropertiessoldnetoperatingincomeyeartodate Segmentreportingsegmentpropertiessoldnetoperatingincomeyeartodate	-13020000	USD
CY2009	eqr	Segmentreportingsegmentpropertiessoldoperatingexpensesyeartodate Segmentreportingsegmentpropertiessoldoperatingexpensesyeartodate	-6762000	USD
CY2010	eqr	Segmentreportingsegmentpropertiessoldoperatingexpensesyeartodate Segmentreportingsegmentpropertiessoldoperatingexpensesyeartodate	-7103000	USD
CY2011	eqr	Segmentreportingsegmentpropertiessoldoperatingexpensesyeartodate Segmentreportingsegmentpropertiessoldoperatingexpensesyeartodate	-7174000	USD
CY2009	eqr	Segmentreportingsegmentpropertiessoldrentalincomeyeartodate Segmentreportingsegmentpropertiessoldrentalincomeyeartodate	-19409000	USD
CY2010	eqr	Segmentreportingsegmentpropertiessoldrentalincomeyeartodate Segmentreportingsegmentpropertiessoldrentalincomeyeartodate	-19024000	USD
CY2011	eqr	Segmentreportingsegmentpropertiessoldrentalincomeyeartodate Segmentreportingsegmentpropertiessoldrentalincomeyeartodate	-20194000	USD
CY2011	eqr	Seller Provided Financing SellerProvidedFinancing	2000000	USD
CY2010	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Forfeited ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanForfeited	-1204	shares
CY2009	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Forfeited ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanForfeited	-573	shares
CY2011	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Forfeited ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanForfeited	-1352	shares
CY2011	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Forfeited Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanForfeitedWeightedAverageGrantDateFairValue	27.79
CY2010	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Forfeited Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanForfeitedWeightedAverageGrantDateFairValue	21.11
CY2009	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Forfeited Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanForfeitedWeightedAverageGrantDateFairValue	21.11
CY2011	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Grants ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanGrants	223452	shares
CY2009	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Grants ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanGrants	155189	shares
CY2010	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Grants ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanGrants	94096	shares
CY2009	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Grants Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanGrantsWeightedAverageGrantDateFairValue	21.11
CY2010	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Grants Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanGrantsWeightedAverageGrantDateFairValue	32.97
CY2011	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Grants Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanGrantsWeightedAverageGrantDateFairValue	46.64
CY2010Q4	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Outstanding ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanOutstanding	247508	shares
CY2011Q4	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Outstanding ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanOutstanding	367620	shares
CY2008Q4	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Outstanding ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanOutstanding	0	shares
CY2009Q4	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Outstanding ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanOutstanding	154616	shares
CY2010Q4	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Units Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanUnitsWeightedAverageGrantDateFairValue	25.62
CY2011Q4	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Units Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanUnitsWeightedAverageGrantDateFairValue	34.80
CY2008Q4	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Units Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanUnitsWeightedAverageGrantDateFairValue	0.00
CY2009Q4	eqr	Share Based Compensation Arrangement By Share Based Payment Award Long Term Incentive Plan Units Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardLongTermIncentivePlanUnitsWeightedAverageGrantDateFairValue	21.11
CY2011Q4	eqr	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized Before Amendment ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorizedBeforeAmendment	2000000	shares
CY2011Q4	eqr	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Purchase Under Employee Share Purchase Plan ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForPurchaseUnderEmployeeSharePurchasePlan	3290863	shares
CY2011	eqr	Share Based Compensation Arrangement By Share Based Payment Award Value Of Common Shares That Can Be Acquired By Employee And Trustees Under Employees Share Purchase Plan ShareBasedCompensationArrangementByShareBasedPaymentAwardValueOfCommonSharesThatCanBeAcquiredByEmployeeAndTrusteesUnderEmployeesSharePurchasePlan	100000	USD
CY2011	eqr	Share Based Compensation Arrangement By Share Based Payment Minimum Discount From Market Price ShareBasedCompensationArrangementByShareBasedPaymentMinimumDiscountFromMarketPrice	0
CY2009	eqr	Share Incentive Plans Dividends Incurred ShareIncentivePlansDividendsIncurred	1881000	USD
CY2010	eqr	Share Incentive Plans Dividends Incurred ShareIncentivePlansDividendsIncurred	1472000	USD
CY2011	eqr	Share Incentive Plans Dividends Incurred ShareIncentivePlansDividendsIncurred	1320000	USD
CY2009	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardequityinstrumentsotherthanoptionsexpiredinperiod Sharebasedcompensationarrangementbysharebasedpaymentawardequityinstrumentsotherthanoptionsexpiredinperiod	0	shares
CY2011	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardequityinstrumentsotherthanoptionsexpiredinperiod Sharebasedcompensationarrangementbysharebasedpaymentawardequityinstrumentsotherthanoptionsexpiredinperiod	0	shares
CY2010	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardequityinstrumentsotherthanoptionsexpiredinperiod Sharebasedcompensationarrangementbysharebasedpaymentawardequityinstrumentsotherthanoptionsexpiredinperiod	0	shares
CY2010	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardequityinstrumentsotherthanoptionsexpiredinperiodweightedaveragegrantdatefairvalue Sharebasedcompensationarrangementbysharebasedpaymentawardequityinstrumentsotherthanoptionsexpiredinperiodweightedaveragegrantdatefairvalue	0.00
CY2011	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardequityinstrumentsotherthanoptionsexpiredinperiodweightedaveragegrantdatefairvalue Sharebasedcompensationarrangementbysharebasedpaymentawardequityinstrumentsotherthanoptionsexpiredinperiodweightedaveragegrantdatefairvalue	0.00
CY2009	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardequityinstrumentsotherthanoptionsexpiredinperiodweightedaveragegrantdatefairvalue Sharebasedcompensationarrangementbysharebasedpaymentawardequityinstrumentsotherthanoptionsexpiredinperiodweightedaveragegrantdatefairvalue	0.00
CY2010	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanexpiredinperiod Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanexpiredinperiod	0	shares
CY2009	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanexpiredinperiod Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanexpiredinperiod	0	shares
CY2011	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanexpiredinperiod Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanexpiredinperiod	0	shares
CY2009	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanexpiredinperiodweightedaveragegrantdatefairvalue Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanexpiredinperiodweightedaveragegrantdatefairvalue	0
CY2011	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanexpiredinperiodweightedaveragegrantdatefairvalue Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanexpiredinperiodweightedaveragegrantdatefairvalue	0
CY2010	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanexpiredinperiodweightedaveragegrantdatefairvalue Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanexpiredinperiodweightedaveragegrantdatefairvalue	0
CY2009	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanvestedexercisedinperiodweightedaveragegrantdatefairvalue Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanvestedexercisedinperiodweightedaveragegrantdatefairvalue	0
CY2011	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanvestedexercisedinperiodweightedaveragegrantdatefairvalue Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanvestedexercisedinperiodweightedaveragegrantdatefairvalue	38.57
CY2010	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanvestedexercisedinperiodweightedaveragegrantdatefairvalue Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanvestedexercisedinperiodweightedaveragegrantdatefairvalue	0
CY2010	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanvestexercisedinperiod Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanvestexercisedinperiod	0	shares
CY2011	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanvestexercisedinperiod Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanvestexercisedinperiod	-101988	shares
CY2009	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanvestexercisedinperiod Sharebasedcompensationarrangementbysharebasedpaymentawardlongtermincentiveplanvestexercisedinperiod	0	shares
CY2011Q4	eqr	Sharebasedcompensationarrangementbysharebasedpaymentawardnumberofsharesauthorizedafteramendment Sharebasedcompensationarrangementbysharebasedpaymentawardnumberofsharesauthorizedafteramendment	7000000	shares
CY2011	eqr	Sharebasedcompensationarrangementbysharebasedpaymentmaximumdiscountfrommarketprice Sharebasedcompensationarrangementbysharebasedpaymentmaximumdiscountfrommarketprice	0.05
CY2009Q4	eqr	Shares Not Settled SharesNotSettled	1100000	shares
CY2011Q4	eqr	Shares Not Settled SharesNotSettled	505438	shares
CY2011	eqr	Stock Issued During Period Shares StockIssuedDuringPeriodShares	3866666	shares
CY2010	eqr	Stock Issued During Period Shares StockIssuedDuringPeriodShares	6151198	shares
CY2009	eqr	Stock Issued During Period Shares StockIssuedDuringPeriodShares	3497300	shares
CY2009	eqr	Stock Options Exercised StockOptionsExercised	-422713	shares
CY2011	eqr	Stock Options Exercised StockOptionsExercised	-2945950	shares
CY2010	eqr	Stock Options Exercised StockOptionsExercised	-2506645	shares
CY2008Q4	eqr	Stock Registered During Period Shares Dividend Reinvestment Plan StockRegisteredDuringPeriodSharesDividendReinvestmentPlan	5000000	shares
CY2011Q4	eqr	Stock Registered During Period Shares Dividend Reinvestment Plan StockRegisteredDuringPeriodSharesDividendReinvestmentPlan	4850000	shares
CY2011	eqr	Stock Repurchased And Retired StockRepurchasedAndRetired	0	shares
CY2010	eqr	Stock Repurchased And Retired StockRepurchasedAndRetired	-58130	shares
CY2009	eqr	Stock Repurchased And Retired StockRepurchasedAndRetired	-47450	shares
CY2012Q1	eqr	Subsequent Event Average Price Per Common Share Issued SubsequentEventAveragePricePerCommonShareIssued	59.47
CY2012Q1	eqr	Subsequent Event Consideration For Shares Issued SubsequentEventConsiderationForSharesIssued	123600000	USD
CY2012Q1	eqr	Subsequent Event Repayment Of Mortgage Loans SubsequentEventRepaymentOfMortgageLoans	31516374	USD
CY2012Q1	eqr	Subsequent Event Sold Consolidated Property SubsequentEventSoldConsolidatedProperty	94825000	USD
CY2012Q1	eqr	Subsequent Event Stock Issued Shares SubsequentEventStockIssuedShares	2075358	shares
CY2011Q4	eqr	Tax Deferred Exchange Proceeds TaxDeferredExchangeProceeds	53668000	USD
CY2010Q4	eqr	Tax Deferred Exchange Proceeds TaxDeferredExchangeProceeds	103887000	USD
CY2009	eqr	Tax Treatment Of Dividends And Distributions Long Term Capital Gain TaxTreatmentOfDividendsAndDistributionsLongTermCapitalGain	0.558
CY2011	eqr	Tax Treatment Of Dividends And Distributions Long Term Capital Gain TaxTreatmentOfDividendsAndDistributionsLongTermCapitalGain	0.629
CY2010	eqr	Tax Treatment Of Dividends And Distributions Long Term Capital Gain TaxTreatmentOfDividendsAndDistributionsLongTermCapitalGain	0.622
CY2011	eqr	Tax Treatment Of Dividends And Distributions Ordinary Dividends TaxTreatmentOfDividendsAndDistributionsOrdinaryDividends	0.667
CY2010	eqr	Tax Treatment Of Dividends And Distributions Ordinary Dividends TaxTreatmentOfDividendsAndDistributionsOrdinaryDividends	0.607
CY2009	eqr	Tax Treatment Of Dividends And Distributions Ordinary Dividends TaxTreatmentOfDividendsAndDistributionsOrdinaryDividends	0.807
CY2011	eqr	Tax Treatment Of Dividends And Distributions Unrecaptured Section Twelve Hundred And Fifty Gain TaxTreatmentOfDividendsAndDistributionsUnrecapturedSectionTwelveHundredAndFiftyGain	0.284
CY2009	eqr	Tax Treatment Of Dividends And Distributions Unrecaptured Section Twelve Hundred And Fifty Gain TaxTreatmentOfDividendsAndDistributionsUnrecapturedSectionTwelveHundredAndFiftyGain	0.275
CY2010	eqr	Tax Treatment Of Dividends And Distributions Unrecaptured Section Twelve Hundred And Fifty Gain TaxTreatmentOfDividendsAndDistributionsUnrecapturedSectionTwelveHundredAndFiftyGain	0.241
CY2012Q1	eqr	Term Loan Facility Spread TermLoanFacilitySpread	0.0125
CY2012Q1	eqr	Term Loan Principal Amount TermLoanPrincipalAmount	500000000	USD
CY2009	eqr	Total Operating Expenses TotalOperatingExpenses	-624643000	USD
CY2011	eqr	Total Operating Expenses TotalOperatingExpenses	-714109000	USD
CY2010	eqr	Total Operating Expenses TotalOperatingExpenses	-686683000	USD
CY2011Q4	eqr	Total Secured And Unsecured Debt TotalSecuredAndUnsecuredDebt	9721061000	USD
CY2010	eqr	Transfer From Notes Net To Mortgage Notes Payable TransferFromNotesNetToMortgageNotesPayable	35600000	USD
CY2009	eqr	Transfer From Notes Net To Mortgage Notes Payable TransferFromNotesNetToMortgageNotesPayable	0	USD
CY2011	eqr	Transfer From Notes Net To Mortgage Notes Payable TransferFromNotesNetToMortgageNotesPayable	0	USD
CY2010Q4	eqr	Unamortized Cash And Conversion Option Discounts UnamortizedCashAndConversionOptionDiscounts	5000000	USD
CY2011	eqr	Unamortized Deferred Financing Costs Written Off UnamortizedDeferredFinancingCostsWrittenOff	4400000	USD
CY2011Q4	eqr	Unconsolidated Project Under Development Commitment Fund UnconsolidatedProjectUnderDevelopmentCommitmentFund	5400000	USD
CY2011Q4	eqr	Units Contracted To Be Acquired UnitsContractedToBeAcquired	648
CY2011Q4	eqr	Units Contracted To Be Disposed UnitsContractedToBeDisposed	1169
CY2009	eqr	Units Issued Conversion Preference Units UnitsIssuedConversionPreferenceUnits	7517	shares
CY2011	eqr	Units Issued During Period New Issues UnitsIssuedDuringPeriodNewIssues	3866666	shares
CY2010	eqr	Units Issued During Period New Issues UnitsIssuedDuringPeriodNewIssues	6200000	shares
CY2009	eqr	Units Issued During Period New Issues UnitsIssuedDuringPeriodNewIssues	3500000	shares
CY2010	eqr	Units Issued To Noncontrolling Interests UnitsIssuedToNoncontrollingInterests	188571	shares
CY2011Q4	eqr	Units Ownership Interest In Operating Partnership UnitsOwnershipInterestInOperatingPartnership	0.043
CY2009Q4	eqr	Units Ownership Interest In Operating Partnership UnitsOwnershipInterestInOperatingPartnership	0.048
CY2010Q4	eqr	Units Ownership Interest In Operating Partnership UnitsOwnershipInterestInOperatingPartnership	0.045
CY2010	eqr	Unrealized Gain Loss On Derivative Instruments Mortgage Notes Payable UnrealizedGainLossOnDerivativeInstrumentsMortgageNotesPayable	-163000	USD
CY2011	eqr	Unrealized Gain Loss On Derivative Instruments Mortgage Notes Payable UnrealizedGainLossOnDerivativeInstrumentsMortgageNotesPayable	-612000	USD
CY2009	eqr	Unrealized Gain Loss On Derivative Instruments Mortgage Notes Payable UnrealizedGainLossOnDerivativeInstrumentsMortgageNotesPayable	-1887000	USD
CY2009	eqr	Unrealized Gain Loss On Derivative Instruments Notes Net UnrealizedGainLossOnDerivativeInstrumentsNotesNet	719000	USD
CY2010	eqr	Unrealized Gain Loss On Derivative Instruments Notes Net UnrealizedGainLossOnDerivativeInstrumentsNotesNet	7497000	USD
CY2011	eqr	Unrealized Gain Loss On Derivative Instruments Notes Net UnrealizedGainLossOnDerivativeInstrumentsNotesNet	-2937000	USD
CY2009	eqr	Unrealized Gain Loss On Derivative Instruments Other Assets UnrealizedGainLossOnDerivativeInstrumentsOtherAssets	-33261000	USD
CY2011	eqr	Unrealized Gain Loss On Derivative Instruments Other Assets UnrealizedGainLossOnDerivativeInstrumentsOtherAssets	6826000	USD
CY2010	eqr	Unrealized Gain Loss On Derivative Instruments Other Assets UnrealizedGainLossOnDerivativeInstrumentsOtherAssets	13019000	USD
CY2010	eqr	Unrealized Gain Loss On Derivative Instruments Other Liabilities UnrealizedGainLossOnDerivativeInstrumentsOtherLiabilities	45542000	USD
CY2009	eqr	Unrealized Gain Loss On Derivative Instruments Other Liabilities UnrealizedGainLossOnDerivativeInstrumentsOtherLiabilities	-3250000	USD
CY2011	eqr	Unrealized Gain Loss On Derivative Instruments Other Liabilities UnrealizedGainLossOnDerivativeInstrumentsOtherLiabilities	140507000	USD
CY2010Q4	eqr	Unsecured Debt Instrument Fair Value UnsecuredDebtInstrumentFairValue	5500000000	USD
CY2011Q4	eqr	Unsecured Debt Instrument Fair Value UnsecuredDebtInstrumentFairValue	6000000000	USD
CY2011	eqr	Valuation Of Op Units Issued ValuationOfOPUnitsIssued	0	USD
CY2010	eqr	Valuation Of Op Units Issued ValuationOfOPUnitsIssued	8245000	USD
CY2009	eqr	Valuation Of Op Units Issued ValuationOfOPUnitsIssued	1034000	USD
CY2011	eqr	Value Of Furniture And Fixtures Maximum Range ValueOfFurnitureAndFixturesMaximumRange	13000	USD
CY2011	eqr	Value Of Furniture And Fixtures Minimum Range ValueOfFurnitureAndFixturesMinimumRange	8000	USD
CY2009	eqr	Value Of Stock Repurchased And Retired ValueOfStockRepurchasedAndRetired	1100000	USD
CY2010	eqr	Value Of Stock Repurchased And Retired ValueOfStockRepurchasedAndRetired	1900000	USD
CY2012Q1	eqr	Valueoflandparcelsacquiredsubsequentevents Valueoflandparcelsacquiredsubsequentevents	12200000	USD
CY2011Q4	eqr	Variable Interest Entity Joint Venture Partner Ownership Percentage VariableInterestEntityJointVenturePartnerOwnershipPercentage	0.50
CY2011Q4	eqr	Various Period Of Outstanding Mortgage Indebtedness VariousPeriodOfOutstandingMortgageIndebtedness	September 1, 2048
CY2010Q4	eqr	Various Period Of Outstanding Mortgage Indebtedness VariousPeriodOfOutstandingMortgageIndebtedness	September 1, 2048
CY2011	eqr	Various Stages Of Development Date Maturity VariousStagesOfDevelopmentDateMaturity	2014-03-31
CY2010	eqr	Weighted Average Mortgage Debt Interest Rate WeightedAverageMortgageDebtInterestRate	0.0479
CY2011	eqr	Weighted Average Mortgage Debt Interest Rate WeightedAverageMortgageDebtInterestRate	0.0484
CY2009	eqr	Weighted Average Number Of Limited Partnership And General Partnership Unit Outstanding Diluted WeightedAverageNumberOfLimitedPartnershipAndGeneralPartnershipUnitOutstandingDiluted	289167000	shares
CY2011	eqr	Weighted Average Number Of Limited Partnership And General Partnership Unit Outstanding Diluted WeightedAverageNumberOfLimitedPartnershipAndGeneralPartnershipUnitOutstandingDiluted	312065000	shares
CY2010	eqr	Weighted Average Number Of Limited Partnership And General Partnership Unit Outstanding Diluted WeightedAverageNumberOfLimitedPartnershipAndGeneralPartnershipUnitOutstandingDiluted	296527000	shares
CY2011Q4	eqr	Wholly Owned Properties WhollyOwnedProperties	404
CY2011Q4	eqr	Wholly Owned Units WhollyOwnedUnits	113157
CY2011	dei	Amendment Flag AmendmentFlag	false
CY2011	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2011	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2011	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2011
CY2011	dei	Document Period End Date DocumentPeriodEndDate	2011-12-31
CY2011	dei	Document Type DocumentType	8-K
CY2011	dei	Entity Central Index Key EntityCentralIndexKey	0000906107
CY2012Q1	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	300240671	shares
CY2011	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2011	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2011Q2	dei	Entity Public Float EntityPublicFloat	17400000000	USD
CY2011	dei	Entity Registrant Name EntityRegistrantName	EQUITY RESIDENTIAL
CY2011	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2011	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes

Files In Submission

Name	View Source	Status
0000906107-12-000019-index-headers.html	Edgar Link	pending
0000906107-12-000019-index.html	Edgar Link	pending
0000906107-12-000019.txt	Edgar Link	pending
0000906107-12-000019-xbrl.zip	Edgar Link	pending
a8-kdiscontinuedoperations.htm	Edgar Link	pending
discops8-kexhibit122011.htm	Edgar Link	pending
discopsexhibit231-eqrconse.htm	Edgar Link	pending
discopsexhibit232-erpopcon.htm	Edgar Link	pending
discopsexhibit9918-keqrx20.htm	Edgar Link	pending
eqr-20120612.xml	Edgar Link	completed
eqr-20120612.xsd	Edgar Link	pending
eqr-20120612_cal.xml	Edgar Link	unprocessable
eqr-20120612_def.xml	Edgar Link	unprocessable
eqr-20120612_lab.xml	Edgar Link	unprocessable
eqr-20120612_pre.xml	Edgar Link	unprocessable
FilingSummary.xml	Edgar Link	unprocessable
Financial_Report.xls	Edgar Link	pending
R1.htm	Edgar Link	pending
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$EQR
EQUITY RESIDENTIAL Stock $eqr

2010 Q4 Form 8-K Financial Statement

#000090610712000019 Filed on June 13, 2012

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$EQR EQUITY RESIDENTIAL Stock $eqr

2010 Q4 Form 8-K Financial Statement

#000090610712000019 Filed on June 13, 2012

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$EQR
EQUITY RESIDENTIAL Stock $eqr