Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies (Details 2)

v2.4.1.9
Summary of Significant Accounting Policies (Details 2) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Quantifying Misstatement in Current Year Financial Statements [Line Items]      
Additional paid-in capital $ 1,969,968us-gaap_AdditionalPaidInCapital $ 1,814,015us-gaap_AdditionalPaidInCapital  
Redeemable noncontrolling interest 18,417us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount 17,758us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount  
Restatement Adjustment | Misapplication of Fair Value Assumptions      
Quantifying Misstatement in Current Year Financial Statements [Line Items]      
Additional paid-in capital     (3,700)us-gaap_AdditionalPaidInCapital
/ us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsByNatureOfErrorAxis
= ofc_MisapplicationofFairValueAssumptionsMember
/ us-gaap_StatementScenarioAxis
= us-gaap_RestatementAdjustmentMember
Redeemable noncontrolling interest     $ 3,700us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount
/ us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsByNatureOfErrorAxis
= ofc_MisapplicationofFairValueAssumptionsMember
/ us-gaap_StatementScenarioAxis
= us-gaap_RestatementAdjustmentMember