Annual report pursuant to Section 13 and 15(d)

Information by Business Segment (Details)

v2.4.1.9
Information by Business Segment (Details) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
segment
Dec. 31, 2013
Dec. 31, 2012
Segment Reporting [Abstract]      
Number of primary office property segments (in number of segments) 10ofc_NumberOfPrimaryOfficePropertySegments    
Segment financial information for real estate operations      
Revenues from real estate operations $ 479,711us-gaap_RealEstateRevenueNet $ 498,633us-gaap_RealEstateRevenueNet $ 493,100us-gaap_RealEstateRevenueNet
Property operating expenses 179,799ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment 180,704ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment 180,735ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
NOI from real estate operations 299,912ofc_SegmentReportingOperatingIncome 317,929ofc_SegmentReportingOperatingIncome 312,365ofc_SegmentReportingOperatingIncome
Segment assets 3,670,257us-gaap_Assets 3,629,952us-gaap_Assets  
Operating Segment Total      
Segment financial information for real estate operations      
Revenues from real estate operations 479,711us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember 		498,633us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember 		493,100us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember
Property operating expenses 179,799ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember 		180,704ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember 		180,735ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember
NOI from real estate operations 299,912ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember 		317,929ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember 		312,365ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember
Additions to long-lived assets 64,601us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember 		56,877us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember 		106,801us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember
Transfers from non-operating properties 141,899ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember 		264,290ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember 		220,997ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember
Segment assets 2,951,495us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember 		2,905,630us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember 		2,945,930us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember
Baltimore and Washington Corridor      
Segment financial information for real estate operations      
Revenues from real estate operations 236,191us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember 		237,869us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember 		238,488us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember
Property operating expenses 81,132ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember 		80,554ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember 		83,050ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember
NOI from real estate operations 155,059ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember 		157,315ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember 		155,438ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember
Additions to long-lived assets 24,174us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember 		28,087us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember 		25,921us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember
Transfers from non-operating properties 56,699ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember 		50,105ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember 		65,108ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember
Segment assets 1,277,600us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember 		1,243,099us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember 		1,267,357us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_BaltimoreAndWashingtonCorridorMember
Northern Virginia      
Segment financial information for real estate operations      
Revenues from real estate operations 89,263us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember 		92,010us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember 		79,574us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember
Property operating expenses 31,532ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember 		31,973ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember 		29,103ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember
NOI from real estate operations 57,731ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember 		60,037ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember 		50,471ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember
Additions to long-lived assets 17,447us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember 		13,090us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember 		65,157us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember
Transfers from non-operating properties 43,154ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember 		61,434ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember 		44,250ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember
Segment assets 642,429us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember 		616,082us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember 		569,860us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NorthernVirginiaMember
San Antonio      
Segment financial information for real estate operations      
Revenues from real estate operations 36,377us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember 		33,060us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember 		32,018us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember
Property operating expenses 20,562ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember 		17,631ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember 		16,499ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember
NOI from real estate operations 15,815ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember 		15,429ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember 		15,519ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember
Additions to long-lived assets (6)us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember 		335us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember 		280us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember
Transfers from non-operating properties 0ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember 		0ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember 		468ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember
Segment assets 116,252us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember 		118,299us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember 		119,369us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_SanAntonioMember
Huntsville      
Segment financial information for real estate operations      
Revenues from real estate operations 10,446us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember 		5,050us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember 		3,867us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember
Property operating expenses 3,066ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember 		1,282ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember 		689ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember
NOI from real estate operations 7,380ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember 		3,768ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember 		3,178ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember
Additions to long-lived assets 4,077us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember 		3,563us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember 		26us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember
Transfers from non-operating properties 21,014ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember 		48,799ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember 		0ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember
Segment assets 97,209us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember 		77,773us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember 		28,730us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_HuntsvilleMember
Washington, DC - Capitol Riverfront      
Segment financial information for real estate operations      
Revenues from real estate operations 14,599us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember 		16,863us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember 		16,697us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember
Property operating expenses 7,308ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember 		7,844ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember 		7,555ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember
NOI from real estate operations 7,291ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember 		9,019ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember 		9,142ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember
Additions to long-lived assets 1,185us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember 		2,604us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember 		317us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember
Transfers from non-operating properties 0ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember 		0ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember 		0ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember
Segment assets 95,195us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember 		98,962us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember 		104,544us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WashingtonDcCapitolRiverfrontMember
St. Mary's and King George Counties      
Segment financial information for real estate operations      
Revenues from real estate operations 16,736us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember 		16,568us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember 		16,392us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember
Property operating expenses 5,268ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember 		5,028ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember 		4,745ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember
NOI from real estate operations 11,468ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember 		11,540ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember 		11,647ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember
Additions to long-lived assets 8,825us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember 		2,341us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember 		1,844us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember
Transfers from non-operating properties 0ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember 		14ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember 		289ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember
Segment assets 100,777us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember 		96,143us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember 		98,027us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_StMarysAndKingGeorgeCountiesMember
Greater Baltimore      
Segment financial information for real estate operations      
Revenues from real estate operations 43,591us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember 		42,653us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember 		52,616us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember
Property operating expenses 17,778ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember 		16,583ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember 		19,917ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember
NOI from real estate operations 25,813ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember 		26,070ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember 		32,699ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember
Additions to long-lived assets 7,925us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember 		2,913us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember 		9,690us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember
Transfers from non-operating properties 3,550ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember 		360ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember 		37,558ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember
Segment assets 274,091us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember 		303,823us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember 		320,548us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterBaltimoreMember
Greater Philadelphia      
Segment financial information for real estate operations      
Revenues from real estate operations 11,929us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember 		11,924us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember 		9,698us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember
Property operating expenses 4,386ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember 		3,431ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember 		2,562ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember
NOI from real estate operations 7,543ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember 		8,493ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember 		7,136ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember
Additions to long-lived assets 952us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember 		406us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember 		286us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember
Transfers from non-operating properties 16,344ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember 		28,034ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember 		10,626ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember
Segment assets 106,931us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember 		104,657us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember 		78,798us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_GreaterPhiladelphiaMember
Colorado Springs      
Segment financial information for real estate operations      
Revenues from real estate operations (1)us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember 		25,290us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember 		24,987us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember
Property operating expenses 12ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember 		9,002ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember 		9,231ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember
NOI from real estate operations (13)ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember 		16,288ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember 		15,756ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember
Additions to long-lived assets 0us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember 		2,940us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember 		2,929us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember
Transfers from non-operating properties 30ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember 		5,438ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember 		4,295ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember
Segment assets 0us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember 		0us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember 		175,830us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_ColoradoSpringsMember
Other      
Segment financial information for real estate operations      
Revenues from real estate operations 10,150us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember 		10,075us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember 		12,116us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember
Property operating expenses 1,469ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember 		1,016ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember 		2,569ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember
NOI from real estate operations 8,681ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember 		9,059ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember 		9,547ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember
Additions to long-lived assets 0us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember 		0us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember 		152us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember
Transfers from non-operating properties 0ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember 		0ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember 		394ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember
Segment assets 77,834us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember 		80,002us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember 		82,090us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_OtherSegmentReportingMember
Operating Wholesale Data Center      
Segment financial information for real estate operations      
Revenues from real estate operations 10,430us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember 		7,271us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember 		6,647us-gaap_RealEstateRevenueNet
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember
Property operating expenses 7,286ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember 		6,360ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember 		4,815ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember
NOI from real estate operations 3,144ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember 		911ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember 		1,832ofc_SegmentReportingOperatingIncome
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember
Additions to long-lived assets 22us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember 		598us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember 		199us-gaap_PropertyPlantAndEquipmentAdditions
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember
Transfers from non-operating properties 1,108ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember 		70,106ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember 		58,009ofc_SegmentReportingTransfersFromNonOperatingProperties
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember
Segment assets $ 163,177us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember 		$ 166,790us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember 		$ 100,777us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_WholesaleDataCenterMember