Name:	ofc_PeriodAfterCessationOfMajorConstructionActivitiesForConsideringPropertyToBeOperationalIfLeasesHaveNotCommencedEarlier
Namespace Prefix:	ofc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the period after the cessation of major construction activities for considering property as partially operational if leases have commenced earlier.

No definition available.

Name:	ofc_PeriodAfterCessationOfMajorConstructionActivitiesForConsideringPropertyToBePartiallyOperationalIfLeasesHaveCommencedEarlier
Namespace Prefix:	ofc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Period used for recovery analysis of long lived assets to be held and used that may be impaired.

No definition available.

Name:	ofc_PeriodusedrecoveryanalysisforPotentiallyImpairedLongLivedAssetHeldandUsed
Namespace Prefix:	ofc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

Name:	us-gaap_PropertyPlantAndEquipmentAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

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.

No definition available.

Name:	us-gaap_PropertyPlantAndEquipmentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

No definition available.

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingAndBuildingImprovementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_LandImprovementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=ofc_EquipmentAndPersonalPropertyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: