Annual report pursuant to Section 13 and 15(d)

Debt (Details 2)

v2.4.1.9
Debt (Details 2) (USD $)
 0 Months Ended 12 Months Ended
Sep. 01, 2011
period
Dec. 31, 2014
period
Dec. 31, 2013
Dec. 31, 2012
Apr. 30, 2014
Schedule on basis of which debt matures          
2015   $ 343,545,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths [1]      
2016   171,399,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo      
2017   339,247,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree [2]      
2018   2,036,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour      
2019   122,094,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive      
Thereafter   951,489,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive      
Total   1,929,810,000us-gaap_DebtInstrumentCarryingAmount [3]      
Debt Instrument [Line Items]          
Debt maturing in 2015 that may be extended for two one year periods   150,000,000ofc_LongtermDebtMaturitiesRepaymentsOfPrincipalDueintheNextTwelveMonthsAmountEligibleforOptionalExtension      
Number of extension option periods for year one long-term debt maturities repayments of principal 2ofc_NumberOfExtensionOptionPeriodsForNextTwelveMonthsLongtermDebtMaturitiesRepaymentsofPrincipal 2ofc_NumberOfExtensionOptionPeriodsForNextTwelveMonthsLongtermDebtMaturitiesRepaymentsofPrincipal      
Extension option period for portion of debt maturing in 2015 (in years)   1 year      
Debt maturing in 2017 that may be extended for a one year period   333,000,000ofc_LongtermDebtMaturitiesRepaymentsOfPrincipalinYearThreeAmountEligibleforOptionalExtension      
Extension option period for portion of debt maturing in 2017 (in years)   1 year      
Net discounts   9,800,000us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet      
Capitalized interest costs   6,100,000us-gaap_InterestCostsCapitalized 8,800,000us-gaap_InterestCostsCapitalized 13,900,000us-gaap_InterestCostsCapitalized  
Wholly Owned Subsidiary          
Debt Instrument [Line Items]          
Debt, net   $ 150,000,000us-gaap_DebtDefaultLongtermDebtAmount
/ dei_LegalEntityAxis
= ofc_WhollyOwnedSubsidiaryMember 		    $ 150,000,000us-gaap_DebtDefaultLongtermDebtAmount
/ dei_LegalEntityAxis
= ofc_WhollyOwnedSubsidiaryMember
[1] Includes $150.0 million pertaining to a nonrecourse mortgage loan on which we defaulted on the payment terms as discussed further below. Also includes $150.0 million that may be extended for two one-year periods at our option, subject to certain conditions.
[2] Includes $333.0 million that may be extended for one year at our option, subject to certain conditions.
[3] Represents scheduled principal amortization and maturities only and therefore excludes net discounts of $9.8 million.