Quarterly report pursuant to Section 13 or 15(d)

Debt (Details)

v2.4.1.9
Debt (Details) (USD $)
 3 Months Ended 0 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Apr. 20, 2015
Dec. 31, 2014
Debt        
Carrying Value $ 1,999,622,000us-gaap_LongTermDebt     $ 1,920,057,000us-gaap_LongTermDebt
Interest costs capitalized 2,100,000us-gaap_InterestCostsCapitalized 1,600,000us-gaap_InterestCostsCapitalized    
Wholly owned subsidiary        
Debt        
Debt Instrument, Debt Default, Amount 150,000,000.0us-gaap_DebtDefaultLongtermDebtAmount
/ dei_LegalEntityAxis
= ofc_WhollyOwnedSubsidiaryMember 		     
Mortgage and Other Secured Loans:        
Debt        
Carrying Value 422,361,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= us-gaap_SecuredDebtMember 		    424,016,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= us-gaap_SecuredDebtMember
Fixed rate mortgage loans        
Debt        
Carrying Value 385,693,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= ofc_FixedRateSecuredDebtMember 		    387,139,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= ofc_FixedRateSecuredDebtMember
Stated interest rates, low end of range (as a percent) 3.96%us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMinimum
/ us-gaap_DebtInstrumentAxis
= ofc_FixedRateSecuredDebtMember 		     
Stated interest rates, high end of range (as a percent) 10.65%us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMaximum
/ us-gaap_DebtInstrumentAxis
= ofc_FixedRateSecuredDebtMember 		     
Unamortized premium included in carrying value 36,000us-gaap_DebtInstrumentUnamortizedPremium
/ us-gaap_DebtInstrumentAxis
= ofc_FixedRateSecuredDebtMember 		    42,000us-gaap_DebtInstrumentUnamortizedPremium
/ us-gaap_DebtInstrumentAxis
= ofc_FixedRateSecuredDebtMember
Weighted average interest rate (as a percent) 8.11%us-gaap_DebtWeightedAverageInterestRate
/ us-gaap_DebtInstrumentAxis
= ofc_FixedRateSecuredDebtMember 		     
Debt, Weighted Average Interest Rate, Excluding Incremental Rate On Default Rate 6.16%ofc_DebtWeightedAverageInterestRateExcludingIncrementalRateOnDefaultRate
/ us-gaap_DebtInstrumentAxis
= ofc_FixedRateSecuredDebtMember 		     
Fixed rate mortgage loans | Maximum        
Debt        
Interest rate excluding incremental rate on default rate (percent) 7.87%ofc_DebtInstrumentInterestRateStatedPercentageExcludingIncrementalRateOnDefaultRate
/ us-gaap_DebtInstrumentAxis
= ofc_FixedRateSecuredDebtMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember 		     
Variable rate secured loans        
Debt        
Carrying Value 36,668,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= ofc_VariableRateSecuredDebtMember 		    36,877,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= ofc_VariableRateSecuredDebtMember
Description of variable rate basis LIBOR      
Stated interest rate (as a percent) 2.42%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= ofc_VariableRateSecuredDebtMember 		     
Variable rate secured loans | London Interbank Offered Rate (LIBOR) [Member]        
Debt        
Variable rate, spread (as a percent) 2.25%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_DebtInstrumentAxis
= ofc_VariableRateSecuredDebtMember
/ us-gaap_VariableRateAxis
= us-gaap_LondonInterbankOfferedRateLIBORMember 		     
Variable rate secured loans | Revolving Credit Facility        
Debt        
Weighted average interest rate (as a percent) 1.45%us-gaap_DebtWeightedAverageInterestRate
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_DebtInstrumentAxis
= ofc_VariableRateSecuredDebtMember 		     
Revolving Credit Facility        
Debt        
Carrying Value 164,000,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= ofc_CreditFacilityMember 		    83,000,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= ofc_CreditFacilityMember
Description of variable rate basis LIBOR      
Revolving Credit Facility | Minimum | London Interbank Offered Rate (LIBOR) [Member]        
Debt        
Variable rate, spread (as a percent) 0.975%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_DebtInstrumentAxis
= ofc_CreditFacilityMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_VariableRateAxis
= us-gaap_LondonInterbankOfferedRateLIBORMember 		     
Revolving Credit Facility | Maximum | London Interbank Offered Rate (LIBOR) [Member]        
Debt        
Variable rate, spread (as a percent) 1.75%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_DebtInstrumentAxis
= ofc_CreditFacilityMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_VariableRateAxis
= us-gaap_LondonInterbankOfferedRateLIBORMember 		     
Revolving Credit Facility | Revolving Credit Facility        
Debt        
Maximum Availability 800,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_DebtInstrumentAxis
= ofc_CreditFacilityMember 		     
Term Loan Facilities        
Debt        
Carrying Value 520,000,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= ofc_TermLoanFacilitiesMember 		    520,000,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= ofc_TermLoanFacilitiesMember
Description of variable rate basis LIBOR      
Weighted average interest rate (as a percent) 1.82%us-gaap_DebtWeightedAverageInterestRate
/ us-gaap_DebtInstrumentAxis
= ofc_TermLoanFacilitiesMember 		     
Additional borrowing capacity available provided there is no default under the agreement 330,000,000ofc_CreditFacilityAdditionalBorrowingCapacityAvailable
/ us-gaap_DebtInstrumentAxis
= ofc_TermLoanFacilitiesMember 		     
Term Loan Facilities | Minimum | London Interbank Offered Rate (LIBOR) [Member]        
Debt        
Variable rate, spread (as a percent) 1.10%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_DebtInstrumentAxis
= ofc_TermLoanFacilitiesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_VariableRateAxis
= us-gaap_LondonInterbankOfferedRateLIBORMember 		     
Term Loan Facilities | Maximum | London Interbank Offered Rate (LIBOR) [Member]        
Debt        
Variable rate, spread (as a percent) 2.60%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_DebtInstrumentAxis
= ofc_TermLoanFacilitiesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_VariableRateAxis
= us-gaap_LondonInterbankOfferedRateLIBORMember 		     
3.60% Senior Notes | Unsecured senior notes        
Debt        
Carrying Value 347,560,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= ofc_A3.60SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		    347,496,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= ofc_A3.60SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember
Stated interest rate (as a percent) 3.60%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= ofc_A3.60SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		     
Interest rate on debt (as a percent) 3.70%us-gaap_DebtInstrumentInterestRateEffectivePercentage
/ us-gaap_DebtInstrumentAxis
= ofc_A3.60SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		     
Debt instrument, face amount 350,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= ofc_A3.60SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		     
Unamortized discount included in carrying value 2,400,000us-gaap_DebtInstrumentUnamortizedDiscount
/ us-gaap_DebtInstrumentAxis
= ofc_A3.60SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		    2,500,000us-gaap_DebtInstrumentUnamortizedDiscount
/ us-gaap_DebtInstrumentAxis
= ofc_A3.60SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember
5.250% Senior Notes | Unsecured senior notes        
Debt        
Carrying Value 245,888,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= ofc_A5.250SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		    245,797,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= ofc_A5.250SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember
Stated interest rate (as a percent) 5.25%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= ofc_A5.250SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		     
Interest rate on debt (as a percent) 5.49%us-gaap_DebtInstrumentInterestRateEffectivePercentage
/ us-gaap_DebtInstrumentAxis
= ofc_A5.250SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		     
Debt instrument, face amount 250,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= ofc_A5.250SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		     
Unamortized discount included in carrying value 4,100,000us-gaap_DebtInstrumentUnamortizedDiscount
/ us-gaap_DebtInstrumentAxis
= ofc_A5.250SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		    4,200,000us-gaap_DebtInstrumentUnamortizedDiscount
/ us-gaap_DebtInstrumentAxis
= ofc_A5.250SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember
3.70% Senior Notes | Unsecured senior notes        
Debt        
Carrying Value 297,655,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= ofc_A3.70SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		    297,569,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= ofc_A3.70SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember
Stated interest rate (as a percent) 3.70%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= ofc_A3.70SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		     
Interest rate on debt (as a percent) 3.85%us-gaap_DebtInstrumentInterestRateEffectivePercentage
/ us-gaap_DebtInstrumentAxis
= ofc_A3.70SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		     
Debt instrument, face amount 300,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= ofc_A3.70SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		     
Unamortized discount included in carrying value 2,300,000us-gaap_DebtInstrumentUnamortizedDiscount
/ us-gaap_DebtInstrumentAxis
= ofc_A3.70SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember 		    2,400,000us-gaap_DebtInstrumentUnamortizedDiscount
/ us-gaap_DebtInstrumentAxis
= ofc_A3.70SeniorNotesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember
Unsecured notes payable        
Debt        
Carrying Value 1,583,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= us-gaap_UnsecuredDebtMember 		    1,607,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= us-gaap_UnsecuredDebtMember
Stated interest rate (as a percent) 0.00%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= us-gaap_UnsecuredDebtMember 		     
Unamortized discount included in carrying value 628,000us-gaap_DebtInstrumentUnamortizedDiscount
/ us-gaap_DebtInstrumentAxis
= us-gaap_UnsecuredDebtMember 		    654,000us-gaap_DebtInstrumentUnamortizedDiscount
/ us-gaap_DebtInstrumentAxis
= us-gaap_UnsecuredDebtMember
4.25% Exchangeable Senior Notes        
Debt        
Carrying Value 575,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= ofc_Exchangeable425PercentSeniorNotesMember 		    572,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= ofc_Exchangeable425PercentSeniorNotesMember
Stated interest rate (as a percent) 4.25%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= ofc_Exchangeable425PercentSeniorNotesMember 		     
Interest rate on debt (as a percent) 6.05%us-gaap_DebtInstrumentInterestRateEffectivePercentage
/ us-gaap_DebtInstrumentAxis
= ofc_Exchangeable425PercentSeniorNotesMember 		     
Unamortized discount included in carrying value       3,000us-gaap_DebtInstrumentUnamortizedDiscount
/ us-gaap_DebtInstrumentAxis
= ofc_Exchangeable425PercentSeniorNotesMember
Exchange rate per $1000 principal amount (in common shares) 20.8513us-gaap_DebtInstrumentConvertibleConversionRatio1
/ us-gaap_DebtInstrumentAxis
= ofc_Exchangeable425PercentSeniorNotesMember 		     
Convertible debt principal amount, basis for exchange 1,000ofc_DebtInstrumentExchangeRatePrincipalAmountUsedInCalculation
/ us-gaap_DebtInstrumentAxis
= ofc_Exchangeable425PercentSeniorNotesMember 		     
Exchange price per common share based on exchange rate (in dollars per share) $ 47.96us-gaap_DebtInstrumentConvertibleConversionPrice1
/ us-gaap_DebtInstrumentAxis
= ofc_Exchangeable425PercentSeniorNotesMember 		     
Principal amount of debt       $ 575,000us-gaap_DebtInstrumentCarryingAmount
/ us-gaap_DebtInstrumentAxis
= ofc_Exchangeable425PercentSeniorNotesMember
4.25% Exchangeable Senior Notes | Subsequent Event        
Debt        
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed     100.00%us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed
/ us-gaap_DebtInstrumentAxis
= ofc_Exchangeable425PercentSeniorNotesMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember 		 
Debt in default of payment terms | Wholly owned subsidiary        
Debt        
Stated interest rate (as a percent) 10.65%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= ofc_DebtinDefaultofPaymentTermsMember
/ dei_LegalEntityAxis
= ofc_WhollyOwnedSubsidiaryMember 		     
Debt in default of payment terms | Wholly owned subsidiary | Northern Virginia        
Debt        
Number of real estate properties 2us-gaap_NumberOfRealEstateProperties
/ us-gaap_DebtInstrumentAxis
= ofc_DebtinDefaultofPaymentTermsMember
/ dei_LegalEntityAxis
= ofc_WhollyOwnedSubsidiaryMember
/ us-gaap_StatementGeographicalAxis
= ofc_NorthernVirginiaMember