COPT Defense Properties Annual report [Section 13 and 15(d), not S-K Item 405]

Annual report [Section 13 and 15(d), not S-K Item 405]

Cover
- Cover Page
- Audit Information
Financial Statements
Notes to Financial Statements
Accounting Policies
- Summary of Significant Accounting Policies (Policies)
Notes Tables
Notes Details

Properties, Net - Narrative (Details)

v3.25.4

Properties, Net - Narrative (Details) ft² in Thousands, $ in Thousands					12 Months Ended
	Oct. 30, 2025 USD ($) ft²	Sep. 26, 2024 USD ($) ft²	Mar. 15, 2024 USD ($) ft²	Jan. 10, 2023 USD ($) property	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Sep. 30, 2024 property	Sep. 30, 2023 property
Real Estate [Line Items]
Number of impaired parcels of land \| property								1	1
Gain on disposal					$ 3,350	$ 0	$ 49,392
Redshift JV LLC
Real Estate [Line Items]
Ownership interest				10.00%	10.00%
Data Center Shells in Northern Virginia \| Disposed of by sale
Real Estate [Line Items]
Ownership percentage sold				90.00%
Number of properties sold \| property				3
Transaction value				$ 211,300
Proceeds from sale				190,200
Gain on disposal				$ 49,400
Other
Real Estate [Line Items]
Number of impaired operating properties \| property									6
Impairment charges							$ 252,800
15050 Conference Center Drive
Real Estate [Line Items]
Area of real estate property (in sqft or acres) \| ft²	142
Asset acquisition, percentage leased	100.00%
Purchase price	$ 40,000
Purchase price, net of purchase price credit	32,600
Purchase price credit	$ 7,400
6841 Benjamin Franklin Drive
Real Estate [Line Items]
Area of real estate property (in sqft or acres) \| ft²			202
Asset acquisition, percentage leased			56.00%
Purchase price			$ 15,000
3900 Rogers Road
Real Estate [Line Items]
Area of real estate property (in sqft or acres) \| ft²		80
Purchase price		$ 17,000

- Definition

Asset Acquisition, Consideration Transferred, Excluding Transaction Costs

+ References

No definition available.

+ Details

Name:	cdp_AssetAcquisitionConsiderationTransferredExcludingTransactionCosts
Namespace Prefix:	cdp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Asset Acquisition, Consideration Transferred, Excluding Transaction Costs, Net Of Purchase Price Credit

+ References

No definition available.

+ Details

Name:	cdp_AssetAcquisitionConsiderationTransferredExcludingTransactionCostsNetOfPurchasePriceCredit
Namespace Prefix:	cdp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Asset Acquisition, Percentage Leased

+ References

No definition available.

+ Details

Name:	cdp_AssetAcquisitionPercentageLeased
Namespace Prefix:	cdp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Asset Acquisition, Purchase Price Credit

+ References

No definition available.

+ Details

Name:	cdp_AssetAcquisitionPurchasePriceCredit
Namespace Prefix:	cdp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number Of Impaired Operating Real Estate Properties

+ References

No definition available.

+ Details

Name:	cdp_NumberOfImpairedOperatingRealEstateProperties
Namespace Prefix:	cdp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number Of Impaired Parcels Of Land

+ References

No definition available.

+ Details

Name:	cdp_NumberOfImpairedParcelsOfLand
Namespace Prefix:	cdp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of Real Estate Properties Sold

+ References

No definition available.

+ Details

Name:	cdp_NumberOfRealEstatePropertiesSold
Namespace Prefix:	cdp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Ownership Percentage Sold

+ References

No definition available.

+ Details

Name:	cdp_OwnershipPercentageSold
Namespace Prefix:	cdp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Area of a real estate property.

+ References

No definition available.

+ Details

Name:	us-gaap_AreaOfRealEstateProperty
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of consideration received or receivable for the disposal of assets and liabilities, including discontinued operation.

+ References

No definition available.

+ Details

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

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 28
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-28

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481687/323-10-50-3

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of gain (loss) on sale or disposal of assets, including but not limited to property plant and equipment, intangible assets and equity in securities of subsidiaries or equity method investee.

+ References

+ Details

Name:	us-gaap_GainLossOnDispositionOfAssets1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The charge against earnings in the period to reduce the carrying amount of real property to fair value.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-28

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 360
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482099/360-10-50-2

+ Details

Name:	us-gaap_ImpairmentOfRealEstate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-12

+ Details

Name:	us-gaap_ProceedsFromDivestitureOfBusinesses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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 976
-SubTopic 310
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477332/976-310-50-1

+ Details

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

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=cdp_RedshiftJVLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=cdp_DataCenterShellsinNorthernVirginiaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=us-gaap_AllOtherSegmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AssetAcquisitionAxis=cdp_A15050ConferenceCenterDriveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AssetAcquisitionAxis=cdp_A6841BenjaminFranklinDriveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AssetAcquisitionAxis=cdp_A3900RogersRoadMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: