Commitments and Contingencies (Details) $ in Millions	Mar. 31, 2024 USD ($) property
Commitments and Contingencies
Estimate of possible loss (up to)	$ 4.6
Environmental Indemnity Agreement
Number of lease properties which were provided environmental indemnifications \| property	3
Maximum environmental indemnification to the tenant against consequential damages after acquisition of property	$ 19.0
Anne Arundel County, Maryland \| Tax Incremental Financing Bond
Environmental Indemnity Agreement
Maximum exposure	$ 27.0

No definition available.

Name:	ofc_EnvironmentalIndemnityAgreementAbstract
Namespace Prefix:	ofc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum additional costs agreed to be paid by the entity under environmental indemnification agreement

+ References

No definition available.

+ Details

Name:	ofc_MaximumAdditionalCostsAgreedToBePaidByTheEntityUnderEnvironmentalIndemnificationAgreement
Namespace Prefix:	ofc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the number of properties in New Jersey which were provided environmental indemnifications by the entity.

+ References

No definition available.

+ Details

Name:	ofc_PropertySubjecttoEnvironmentalIndemnityNumberofProperties
Namespace Prefix:	ofc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482425/460-10-50-4

+ Details

Name:	us-gaap_GuaranteeObligationsMaximumExposure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482425/460-10-50-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483076/450-20-50-1

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483076/450-20-50-4

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483076/450-20-50-4

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483076/450-20-50-9

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483076/450-20-50-9

+ Details

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

- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

+ References

+ Details

Name:	us-gaap_LossContingencyEstimateOfPossibleLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	srt_CounterpartyNameAxis=ofc_AnneArundelCountyMarylandMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OtherCommitmentsAxis=ofc_TaxIncrementalFinancingBondMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: