Quarterly report pursuant to Section 13 or 15(d)

Properties, net (Details 2)

v2.4.1.9
Properties, net (Details 2) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Properties    
Projects in development or held for future development $ 489,618us-gaap_DevelopmentInProcess $ 545,426us-gaap_DevelopmentInProcess
Assets held for sale, net 0us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation 14,339us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation
Greater Baltimore    
Properties    
Number of properties held-for-sale   2ofc_NumberofRealEstatePropertiesAssetsHeldforsale
/ ofc_RealEstatePropertyDisposalAxis
= ofc_GreaterBaltimoreMember
Assets held for sale, net   14,300us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation
/ ofc_RealEstatePropertyDisposalAxis
= ofc_GreaterBaltimoreMember
Projects in development or held for future development | Land in development or held for future development    
Properties    
Projects in development or held for future development 219,852us-gaap_DevelopmentInProcess
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= ofc_LandInDevelopmentOrHeldForFutureDevelopmentMember
/ ofc_RealEstatePropertiesStatusAxis
= ofc_ProjectsInDevelopmentOrHeldForFutureDevelopmentMember 		214,977us-gaap_DevelopmentInProcess
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= ofc_LandInDevelopmentOrHeldForFutureDevelopmentMember
/ ofc_RealEstatePropertiesStatusAxis
= ofc_ProjectsInDevelopmentOrHeldForFutureDevelopmentMember
Projects in development or held for future development | Construction in progress, excluding land    
Properties    
Projects in development or held for future development $ 269,766us-gaap_DevelopmentInProcess
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_ConstructionInProgressMember
/ ofc_RealEstatePropertiesStatusAxis
= ofc_ProjectsInDevelopmentOrHeldForFutureDevelopmentMember 		$ 330,449us-gaap_DevelopmentInProcess
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_ConstructionInProgressMember
/ ofc_RealEstatePropertiesStatusAxis
= ofc_ProjectsInDevelopmentOrHeldForFutureDevelopmentMember