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Fair Value Measurements (Details 2) (USD $) In Thousands, unless otherwise specified | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
--- | --- | --- | --- | ---
Liabilities: |  |  |  |  |  |
Interest rate derivatives | $ 1,855 us-gaap_InterestRateDerivativeLiabilitiesAtFairValue |  | $ 3,309 us-gaap_InterestRateDerivativeLiabilitiesAtFairValue |  |  |
Redeemable noncontrolling interest | 18,417 us-gaap_RedeemableNoncontrollingInterestEquityFairValue |  | 17,758 us-gaap_RedeemableNoncontrollingInterestEquityFairValue |  | 10,298 us-gaap_RedeemableNoncontrollingInterestEquityFairValue | 8,908 us-gaap_RedeemableNoncontrollingInterestEquityFairValue
Corporate Office Properties, L.P. |  |  |  |  |  |
Liabilities: |  |  |  |  |  |
Interest rate derivatives | 1,855 us-gaap_InterestRateDerivativeLiabilitiesAtFairValue / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  | 3,309 us-gaap_InterestRateDerivativeLiabilitiesAtFairValue / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  |  |
Fair value measurement on a recurring basis |  |  |  |  |  |
Assets: |  |  |  |  |  |
Common stocks |  |  | 298 us-gaap_MarketableSecuritiesEquitySecurities / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [1] |  |
Interest rate derivatives | 274 us-gaap_InterestRateDerivativeAssetsAtFairValue / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [2] | 6,594 us-gaap_InterestRateDerivativeAssetsAtFairValue / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [2] |  |
Warrants to purchase common stock in KEYW | 164 ofc_WarrantsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [2] | 301 ofc_WarrantsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [2] |  |
Assets | 6,320 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 14,660 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |  |
Liabilities: |  |  |  |  |  |
Deferred compensation plan liability | 5,882 us-gaap_DeferredCompensationLiabilityCurrentAndNoncurrent / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [3] | 7,467 us-gaap_DeferredCompensationLiabilityCurrentAndNoncurrent / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [3] |  |
Interest rate derivatives | 1,855 us-gaap_InterestRateDerivativeLiabilitiesAtFairValue / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 3,309 us-gaap_InterestRateDerivativeLiabilitiesAtFairValue / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |  |
Liabilities | 7,737 us-gaap_LiabilitiesFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 10,776 us-gaap_LiabilitiesFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |  |
Redeemable noncontrolling interest | 18,417 us-gaap_RedeemableNoncontrollingInterestEquityFairValue / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 17,758 us-gaap_RedeemableNoncontrollingInterestEquityFairValue / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |  |
Fair value measurement on a recurring basis | Mutual funds |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable securities in deferred compensation plan | 5,756 us-gaap_DeferredCompensationPlanAssets / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_EquityFundsMember | [1] | 7,090 us-gaap_DeferredCompensationPlanAssets / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_EquityFundsMember | [1] |  |
Fair value measurement on a recurring basis | Common Shares |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable securities in deferred compensation plan |  |  | 176 us-gaap_DeferredCompensationPlanAssets / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_CommonStockMember | [1] |  |
Fair value measurement on a recurring basis | Other |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable securities in deferred compensation plan | 126 us-gaap_DeferredCompensationPlanAssets / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = ofc_OtherMarketableSecuritiesMember | [1] | 201 us-gaap_DeferredCompensationPlanAssets / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = ofc_OtherMarketableSecuritiesMember | [1] |  |
Fair value measurement on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |  |  |
Assets: |  |  |  |  |  |
Common stocks |  |  | 298 us-gaap_MarketableSecuritiesEquitySecurities / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [1] |  |
Assets | 5,882 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 7,765 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |  |
Liabilities: |  |  |  |  |  |
Liabilities | 0 us-gaap_LiabilitiesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 0 us-gaap_LiabilitiesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |  |
Fair value measurement on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mutual funds |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable securities in deferred compensation plan | 5,756 us-gaap_DeferredCompensationPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_EquityFundsMember | [1] | 7,090 us-gaap_DeferredCompensationPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_EquityFundsMember | [1] |  |
Fair value measurement on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Common Shares |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable securities in deferred compensation plan |  |  | 176 us-gaap_DeferredCompensationPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_CommonStockMember | [1] |  |
Fair value measurement on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other |  |  |  |  |  |
Assets: |  |  |  |  |  |
Marketable securities in deferred compensation plan | 126 us-gaap_DeferredCompensationPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = ofc_OtherMarketableSecuritiesMember | [1] | 201 us-gaap_DeferredCompensationPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = ofc_OtherMarketableSecuritiesMember | [1] |  |
Fair value measurement on a recurring basis | Significant Other Observable Inputs (Level 2) |  |  |  |  |  |
Assets: |  |  |  |  |  |
Interest rate derivatives | 274 us-gaap_InterestRateDerivativeAssetsAtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [2] | 6,594 us-gaap_InterestRateDerivativeAssetsAtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [2] |  |
Warrants to purchase common stock in KEYW | 164 ofc_WarrantsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [2] | 301 ofc_WarrantsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [2] |  |
Assets | 438 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 6,895 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |  |
Liabilities: |  |  |  |  |  |
Deferred compensation plan liability | 5,882 us-gaap_DeferredCompensationLiabilityCurrentAndNoncurrent / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [3] | 7,467 us-gaap_DeferredCompensationLiabilityCurrentAndNoncurrent / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [3] |  |
Interest rate derivatives | 1,855 us-gaap_InterestRateDerivativeLiabilitiesAtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 3,309 us-gaap_InterestRateDerivativeLiabilitiesAtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |  |
Liabilities | 7,737 us-gaap_LiabilitiesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 10,776 us-gaap_LiabilitiesFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |  |
Fair value measurement on a recurring basis | Significant Unobservable Inputs (Level 3) |  |  |  |  |  |
Liabilities: |  |  |  |  |  |
Redeemable noncontrolling interest | 18,417 us-gaap_RedeemableNoncontrollingInterestEquityFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 17,758 us-gaap_RedeemableNoncontrollingInterestEquityFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |  |
Fair value measurement on a recurring basis | Corporate Office Properties, L.P. |  |  |  |  |  |
Assets: |  |  |  |  |  |
Common stocks |  |  | 298 us-gaap_MarketableSecuritiesEquitySecurities / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember | [4] |  |
Interest rate derivatives | 274 us-gaap_InterestRateDerivativeAssetsAtFairValue / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember | [5] | 6,594 us-gaap_InterestRateDerivativeAssetsAtFairValue / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember | [5] |  |
Warrants to purchase common stock in KEYW | 164 ofc_WarrantsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember | [5] | 301 ofc_WarrantsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember | [5] |  |
Assets | 438 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  | 7,193 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  |  |
Liabilities: |  |  |  |  |  |
Interest rate derivatives | 1,855 us-gaap_InterestRateDerivativeLiabilitiesAtFairValue / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  | 3,309 us-gaap_InterestRateDerivativeLiabilitiesAtFairValue / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  |  |
Redeemable noncontrolling interest | 18,417 us-gaap_RedeemableNoncontrollingInterestEquityFairValue / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  | 17,758 us-gaap_RedeemableNoncontrollingInterestEquityFairValue / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  |  |
Fair value measurement on a recurring basis | Corporate Office Properties, L.P. | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |  |  |
Assets: |  |  |  |  |  |
Common stocks |  |  | 298 us-gaap_MarketableSecuritiesEquitySecurities / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember | [4] |  |
Assets | 0 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  | 298 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  |  |
Fair value measurement on a recurring basis | Corporate Office Properties, L.P. | Significant Other Observable Inputs (Level 2) |  |  |  |  |  |
Assets: |  |  |  |  |  |
Interest rate derivatives | 274 us-gaap_InterestRateDerivativeAssetsAtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember | [5] | 6,594 us-gaap_InterestRateDerivativeAssetsAtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember | [5] |  |
Warrants to purchase common stock in KEYW | 164 ofc_WarrantsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember | [5] | 301 ofc_WarrantsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember | [5] |  |
Assets | 438 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  | 6,895 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  |  |
Liabilities: |  |  |  |  |  |
Interest rate derivatives | 1,855 us-gaap_InterestRateDerivativeLiabilitiesAtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  | 3,309 us-gaap_InterestRateDerivativeLiabilitiesAtFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  |  |
Fair value measurement on a recurring basis | Corporate Office Properties, L.P. | Significant Unobservable Inputs (Level 3) |  |  |  |  |  |
Assets: |  |  |  |  |  |
Assets | 0 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  | 0 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  |  |
Liabilities: |  |  |  |  |  |
Redeemable noncontrolling interest | $ 18,417 us-gaap_RedeemableNoncontrollingInterestEquityFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  | $ 17,758 us-gaap_RedeemableNoncontrollingInterestEquityFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  |  |
[1] | Included in the line entitled “restricted cash and marketable securities” on COPT’s consolidated balance sheet.
[2] | Included in the line entitled “prepaid expenses and other assets” on COPT’s consolidated balance sheet.
[3] | Included in the line entitled “other liabilities” on COPT’s consolidated balance sheet.
[4] | Included in the line entitled “restricted cash and marketable securities” on COPLP’s consolidated balance sheet.
[5] | Included in the line entitled “prepaid expenses and other assets” on COPLP’s consolidated balance sheet.

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- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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- Definition For an unclassified balance sheet, this item represents investments in common and preferred stocks and other forms of securities that provide ownership interests in a corporation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 1 -Subparagraph b -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.1(b)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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- Definition The aggregate fair value as of the reporting date of all noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. This item includes noncontrolling interest holder's ownership (or holders' ownership) regardless of the type of equity interest (common, preferred, other) including all potential organizational (legal) forms of the investee entity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 480 -SubTopic 10 -Section S99 -Paragraph 3A -Subparagraph 14 -URI http://asc.fasb.org/extlink&oid=27011957&loc=SL6540498-122764 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 480 -SubTopic 10 -Section S99 -Paragraph 3A -Subparagraph (16)(c) -URI http://asc.fasb.org/extlink&oid=27011957&loc=SL6540498-122764 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 480 -SubTopic 10 -Section S99 -Paragraph 3A -Subparagraph 15 -URI http://asc.fasb.org/extlink&oid=27011957&loc=SL6540498-122764 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 480 -SubTopic 10 -Section S99 -Paragraph 3A -Subparagraph (12)(c) -URI http://asc.fasb.org/extlink&oid=27011957&loc=SL6540498-122764 + Details
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