Annual report pursuant to Section 13 and 15(d)

Concentration of Rental Revenue (Details)

v2.4.1.9
Concentration of Rental Revenue (Details)
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Concentration Risk      
Number of regions with real estate operations which are not located in the Mid-Atlantic region of the United States 3ofc_ConcentrationRiskNumberOfRegionsWithRealEstateOperationsNotLocatedInMidAtlanticRegionOfUnitedStates    
Rental revenue | Tenants      
Concentration Risk      
Percentage required for qualification as major customer 5.00%ofc_ThresholdForDisclosurePercentage
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_RentalRevenueMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember 		   
Number of tenants from which the entity has recognized the most rental revenue aggregated for revenue concentration disclosure 5ofc_ConcentrationRiskNumberOfTenantsFromWhichEntityHasRecognizedMostRentalRevenueAggregatedForRevenueConcentrationDisclosure
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_RentalRevenueMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember 		   
Rental revenue | Tenants | United States Government      
Concentration Risk      
Percentage of revenue 18.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_RentalRevenueMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= ofc_UnitedStatesGovernmentMember 		18.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_RentalRevenueMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= ofc_UnitedStatesGovernmentMember 		18.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_RentalRevenueMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= ofc_UnitedStatesGovernmentMember
Rental revenue | Tenants | Northrop Grumman Corporation      
Concentration Risk      
Percentage of revenue 6.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_RentalRevenueMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= ofc_NorthropGrummanCorporationMember 		[1] 8.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_RentalRevenueMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= ofc_NorthropGrummanCorporationMember 		[1] 7.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_RentalRevenueMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= ofc_NorthropGrummanCorporationMember 		[1]
Rental revenue | Tenants | Booz Allen Hamilton, Inc.      
Concentration Risk      
Percentage of revenue 6.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_RentalRevenueMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= ofc_BoozAllenHamiltonIncMember 		6.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_RentalRevenueMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= ofc_BoozAllenHamiltonIncMember 		6.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_RentalRevenueMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= ofc_BoozAllenHamiltonIncMember
Rental revenue | Tenants | Computer Sciences Corporation      
Concentration Risk      
Percentage of revenue   5.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_RentalRevenueMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= ofc_ComputerSciencesCorporationMember 		[1] 5.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_RentalRevenueMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= ofc_ComputerSciencesCorporationMember 		[1]
Rental revenue | Tenants | Five largest tenants      
Concentration Risk      
Percentage of revenue 39.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_RentalRevenueMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= ofc_FiveLargestTenantsMember 		41.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_RentalRevenueMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= ofc_FiveLargestTenantsMember 		39.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_RentalRevenueMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= ofc_FiveLargestTenantsMember
Construction contract revenue | United States Government      
Concentration Risk      
Percentage of revenue 90.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_ConstructionContractRevenueMember
/ us-gaap_MajorCustomersAxis
= ofc_UnitedStatesGovernmentMember 		90.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_ConstructionContractRevenueMember
/ us-gaap_MajorCustomersAxis
= ofc_UnitedStatesGovernmentMember 		90.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= ofc_ConstructionContractRevenueMember
/ us-gaap_MajorCustomersAxis
= ofc_UnitedStatesGovernmentMember
[1] Includes affiliated organizations and agencies and predecessor companies.