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v2.4.0.8

Properties, net (Details 4) | 9 Months Ended
--- | ---
Sep. 30, 2013 Property sqft
Newly constructed properties placed in service |
Construction and Redevelopment Activities |
Square Feet of Properties Placed in Service | 392,000
Number of Real Estate Properties Placed In Service | 4
Properties under construction or contractually committed for construction |
Construction and Redevelopment Activities |
Number of real estate properties | 9
Square footage of real estate properties (in square feet) | 1,300,000
Properties under construction or contractually committed for construction | Northern Virginia |
Construction and Redevelopment Activities |
Number of real estate properties | 4
Properties under construction or contractually committed for construction | Baltimore and Washington Corridor |
Construction and Redevelopment Activities |
Number of real estate properties | 2
Properties under construction or contractually committed for construction | Huntsville |
Construction and Redevelopment Activities |
Number of real estate properties | 3
Properties under or approved for redevelopment |
Construction and Redevelopment Activities |
Number of real estate properties | 2
Square footage of real estate properties (in square feet) | 235,000
Properties under or approved for redevelopment | Baltimore and Washington Corridor |
Construction and Redevelopment Activities |
Number of real estate properties | 1
Properties under or approved for redevelopment | Greater Philadelphia |
Construction and Redevelopment Activities |
Number of real estate properties | 1

X
- Definition Represents the number of real estate properties placed in service during the year. + References No definition available. + Details
Name: | ofc_NumberOfRealEstatePropertiesPlacedInService
Namespace Prefix: | ofc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of square footage placed into service during the period. + References No definition available. + Details
Name: | ofc_SquareFeetOfPropertiesPlacedInService
Namespace Prefix: | ofc_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | duration

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
- Details
Name: | us-gaap_RealEstatePropertiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration