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Indebtedness Unsecured Debt (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2015
loans
Mar. 31, 2014
Dec. 31, 2014
Debt Instrument [Line Items]      
Number of Variable Rate Unsecured Loans 1dre_NumberofVariableRateUnsecuredLoans    
Long-term Debt $ 4,444,368us-gaap_LongTermDebt   $ 4,412,639us-gaap_LongTermDebt
Repayments of Unsecured Debt 250,544us-gaap_RepaymentsOfUnsecuredDebt 511us-gaap_RepaymentsOfUnsecuredDebt  
Variable Rate UnSecured Debt [Member] [Member]      
Debt Instrument [Line Items]      
Long-term Debt 250,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= dre_VariableRateUnSecuredDebtMemberMember
   
Debt Instrument, Interest Rate, Effective Percentage 1.33%us-gaap_DebtInstrumentInterestRateEffectivePercentage
/ us-gaap_DebtInstrumentAxis
= dre_VariableRateUnSecuredDebtMemberMember
   
Fixed Rate Unsecured Debt [Member]      
Debt Instrument [Line Items]      
Debt Instrument, Estimated Trading Values, Percent of Face Value, Minimum 102.00%dre_DebtInstrumentEstimatedTradingValuesPercentOfFaceValueMinimum
/ us-gaap_DebtInstrumentAxis
= dre_FixedRateUnsecuredDebtMember
   
Debt Instrument, Estimated Trading Values, Percent of Face Value, Maximum 131.00%dre_DebtInstrumentEstimatedTradingValuesPercentOfFaceValueMaximum
/ us-gaap_DebtInstrumentAxis
= dre_FixedRateUnsecuredDebtMember
   
Debt Instrument, Covenant Compliance We were in compliance with all such covenants at March 31, 2015    
Fixed Rate Unsecured Debt Repaid [Member]      
Debt Instrument [Line Items]      
Debt Instrument, Interest Rate, Effective Percentage 7.50%us-gaap_DebtInstrumentInterestRateEffectivePercentage
/ us-gaap_DebtInstrumentAxis
= dre_FixedRateUnsecuredDebtRepaidMember
   
Repayments of Unsecured Debt $ 250,000us-gaap_RepaymentsOfUnsecuredDebt
/ us-gaap_DebtInstrumentAxis
= dre_FixedRateUnsecuredDebtRepaidMember
   
Debt Instrument, Interest Rate, Stated Percentage 7.38%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= dre_FixedRateUnsecuredDebtRepaidMember