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v3.20.1

Properties, Net - 2020 Development Activities (Details) ft² in Thousands | Mar. 31, 2020 ft² property
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Newly developed properties placed in service |
Real Estate [Line Items] |
Area of real estate property (in sqft or acres) | ft² | 230
Number of real estate properties | property | 1
Properties under development or contractually committed for construction |
Real Estate [Line Items] |
Area of real estate property (in sqft or acres) | ft² | 2,200
Number of real estate properties | property | 13
Properties under or approved for redevelopment partially-operational |
Real Estate [Line Items] |
Area of real estate property (in sqft or acres) | ft² | 106
Number of real estate properties | property | 1

X
- Definition Area of a real estate property. + References No definition available. + Details
Name: | us-gaap_AreaOfRealEstateProperty
Namespace Prefix: | us-gaap_
Data Type: | num:areaItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of real estate properties owned as of the balance sheet date. + References No definition available. + Details
Name: | us-gaap_NumberOfRealEstateProperties
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_RealEstateLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RealEstatePropertiesAxis=ofc_NewlyDevelopedPropertiesPlacedinServiceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstatePropertiesAxis=ofc_PropertiesunderDevelopmentorContractuallyCommitedforConstructionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstatePropertiesAxis=ofc_PropertiesUnderOrApprovedForRedevelopmentPartiallyOperationalMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |