Quarterly report pursuant to Section 13 or 15(d)

Real Estate Joint Ventures (Details)

v2.4.1.9
Real Estate Joint Ventures (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Consolidated real estate joint ventures  
Investments in consolidated real estate joint ventures  
Total Assets $ 208,769us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryAggregatedDisclosureMember
Encumbered Assets 114,414us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryAggregatedDisclosureMember
Total Liabilities 82,014us-gaap_VariableInterestEntityConsolidatedCarryingAmountLiabilities
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryAggregatedDisclosureMember
LW Redstone Company, LLC  
Investments in consolidated real estate joint ventures  
Buildings Operated by Joint Ventures Number 4ofc_BuildingsOperatedbyJointVenturesNumber
/ us-gaap_CounterpartyNameAxis
= ofc_LwRedstoneCompanyLlcMember
LW Redstone Company, LLC | Variable Interest Entity, Primary Beneficiary [Member]  
Investments in consolidated real estate joint ventures  
Ownership (as a percent) 85.00%us-gaap_VariableInterestEntityOwnershipPercentage
/ us-gaap_CounterpartyNameAxis
= ofc_LwRedstoneCompanyLlcMember
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Total Assets 149,098us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets
/ us-gaap_CounterpartyNameAxis
= ofc_LwRedstoneCompanyLlcMember
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Encumbered Assets 65,934us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate
/ us-gaap_CounterpartyNameAxis
= ofc_LwRedstoneCompanyLlcMember
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Total Liabilities 43,314us-gaap_VariableInterestEntityConsolidatedCarryingAmountLiabilities
/ us-gaap_CounterpartyNameAxis
= ofc_LwRedstoneCompanyLlcMember
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
M Square Associates, LLC  
Investments in consolidated real estate joint ventures  
Buildings Operated by Joint Ventures Number 2ofc_BuildingsOperatedbyJointVenturesNumber
/ us-gaap_CounterpartyNameAxis
= ofc_MSquareAssociatesLlcMember
M Square Associates, LLC | Variable Interest Entity, Primary Beneficiary [Member]  
Investments in consolidated real estate joint ventures  
Ownership (as a percent) 50.00%us-gaap_VariableInterestEntityOwnershipPercentage
/ us-gaap_CounterpartyNameAxis
= ofc_MSquareAssociatesLlcMember
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Total Assets 59,671us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets
/ us-gaap_CounterpartyNameAxis
= ofc_MSquareAssociatesLlcMember
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Encumbered Assets 48,480us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate
/ us-gaap_CounterpartyNameAxis
= ofc_MSquareAssociatesLlcMember
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Total Liabilities $ 38,700us-gaap_VariableInterestEntityConsolidatedCarryingAmountLiabilities
/ us-gaap_CounterpartyNameAxis
= ofc_MSquareAssociatesLlcMember
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember