Annual report pursuant to Section 13 and 15(d)

Organization (Details 2)

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Organization (Details 2) (Corporate Office Properties, L.P.)
 12 Months Ended
Dec. 31, 2014
Common Units
  
Forms of ownership in Operating Partnership and ownership percentage by the entity  
Percentage ownership in operating partnership 96.00%us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest
/ dei_LegalEntityAxis
= ofc_CorporateOfficePropertiesLPMember
/ ofc_UnitsByNameAxis
= ofc_CommonUnitsMember
Preferred Units
  
Forms of ownership in Operating Partnership and ownership percentage by the entity  
Percentage ownership in operating partnership 95.50%us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest
/ dei_LegalEntityAxis
= ofc_CorporateOfficePropertiesLPMember
/ ofc_UnitsByNameAxis
= ofc_PreferredUnitsMember