XML 27 R70.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Real Estate Joint Ventures (Details) (USD $) | 12 Months Ended | 0 Months Ended | 12 Months Ended | 0 Months Ended
--- | --- | --- | --- | ---
Dec. 31, 2014 buillding sqft | Sep. 17, 2013 | Dec. 11, 2013 | Dec. 31, 2013 | Dec. 31, 2012 Property | Aug. 07, 2014
Investments in consolidated real estate joint ventures |  |  |  |  |  |  |
Investing receivables | $ 52,147,000 us-gaap_NotesReceivableNet |  |  |  | $ 53,663,000 us-gaap_NotesReceivableNet |  |
LW Redstone Company, LLC |  |  |  |  |  |  |
Investments in consolidated real estate joint ventures |  |  |  |  |  |  |
Number of buildings operated by the joint venture | 4 ofc_BuildingsOperatedByJointVenturesNumber / dei_LegalEntityAxis = ofc_LwRedstoneCompanyLlcMember |  |  |  |  |  |
Partner's capital account upon formation | 9,000,000 ofc_PartnersCapitalAccountUponFormation / dei_LegalEntityAxis = ofc_LwRedstoneCompanyLlcMember |  |  |  |  |  |
Percentage of residual distributable cash flows in excess of unpaid cumulative preferred returns and return of invested capital entitled to the company | 85.00%ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCapital / dei_LegalEntityAxis = ofc_LwRedstoneCompanyLlcMember |  |  |  |  |  |
Percentage of residual distributable cash flows in excess of unpaid cumulative preferred returns and return of invested capital entitled to the entity's partners | 15.00%ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCashRelatedToRealEstatePartner / dei_LegalEntityAxis = ofc_LwRedstoneCompanyLlcMember |  |  |  |  |  |
Number of years following construction commencement threshold achievement before partner's interest can be purchased at fair value | 5 years |  |  |  |  |  |
Construction commencement threshold (in square feet) | 4,400,000.0 ofc_ConstructionCommencementThreshold / dei_LegalEntityAxis = ofc_LwRedstoneCompanyLlcMember |  |  |  |  |  |
Construction Commencement Threshold, Completed | 561,000 ofc_ConstructionCommencementThresholdCompleted / dei_LegalEntityAxis = ofc_LwRedstoneCompanyLlcMember |  |  |  |  |  |
LW Redstone Company, LLC | Maximum |  |  |  |  |  |  |
Investments in consolidated real estate joint ventures |  |  |  |  |  |  |
Infrastructure costs anticipated to be funded by entity for reimbursement by the City of Huntsville (in dollars) | 76,000,000 ofc_InfrastructureCostsAnticipatedToBeFunded / dei_LegalEntityAxis = ofc_LwRedstoneCompanyLlcMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  |  |  |  |  |
M Square Associates, LLC |  |  |  |  |  |  |
Investments in consolidated real estate joint ventures |  |  |  |  |  |  |
Number of buildings operated by the joint venture | 2 ofc_BuildingsOperatedByJointVenturesNumber / dei_LegalEntityAxis = ofc_MSquareAssociatesLlcMember |  |  |  |  |  |
Percentage of residual amounts distributed to each member | 50.00%ofc_PercentageOfResidualNetCashFlowDistributedToEachPartner / dei_LegalEntityAxis = ofc_MSquareAssociatesLlcMember |  |  |  |  |  |
Consolidated real estate joint ventures |  |  |  |  |  |  |
Investments in consolidated real estate joint ventures |  |  |  |  |  |  |
Total Assets | 202,948,000 us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets / dei_LegalEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryAggregatedDisclosureMember | [1] |  |  |  |  |
Encumbered Assets | 115,476,000 us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate / dei_LegalEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryAggregatedDisclosureMember | [1] |  |  |  |  |
Total Liabilities | 80,736,000 us-gaap_VariableInterestEntityConsolidatedCarryingAmountLiabilities / dei_LegalEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryAggregatedDisclosureMember | [1] |  |  |  |  |
Arundel Preserve 5, LLC |  |  |  |  |  |  |
Investments in consolidated real estate joint ventures |  |  |  |  |  |  |
Ownership (as a percent) |  |  | 50.00%us-gaap_VariableInterestEntityOwnershipPercentage / dei_LegalEntityAxis = ofc_ArundelPreserveLlcMember |  |  |  |
Arundel Preserve 5, LLC | Common Shares |  |  |  |  |  |  |
Investments in consolidated real estate joint ventures |  |  |  |  |  |  |
Acquisition of property and noncontrolling interest in other consolidated entity for COPLP common units (in units) |  |  | 221,501 us-gaap_StockIssuedDuringPeriodSharesAcquisitions / dei_LegalEntityAxis = ofc_ArundelPreserveLlcMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember |  |  |  |
Acquisition of property and noncontrolling interest in other consolidated entity for COPLP common units (in dollars) |  |  | 5,200,000 us-gaap_StockIssuedDuringPeriodValueAcquisitions / dei_LegalEntityAxis = ofc_ArundelPreserveLlcMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember |  |  |  |
MOR Forbes 2 LLC |  |  |  |  |  |  |
Investments in consolidated real estate joint ventures |  |  |  |  |  |  |
Ownership (as a percent) |  |  |  | 50.00%us-gaap_VariableInterestEntityOwnershipPercentage / dei_LegalEntityAxis = ofc_MorForbes2LlcMember |  |  |
Unconsolidated real estate joint ventures |  |  |  |  |  |  |
Investments in consolidated real estate joint ventures |  |  |  |  |  |  |
Ownership (as a percent) |  |  |  |  |  | 20.00%us-gaap_VariableInterestEntityOwnershipPercentage / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember |
Number of buildings operated by the joint venture |  |  |  |  |  | 16 ofc_BuildingsOperatedByJointVenturesNumber / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember |
Investment balance |  |  |  |  |  | (6,400,000)ofc_DistributionsReceivedInExcessOfInvestmentInUnconsolidatedRealEstateJointVenture / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember |
Difference between carrying amount of investment and share of the equity in the joint venture |  |  |  |  |  | 4,500,000 us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember |
Gain on disposal |  |  |  |  | 6,300,000 us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember |  |
Condensed statements of operations for unconsolidated real estate joint venture |  |  |  |  |  |  |
Revenues |  |  |  |  | 6,519,000 us-gaap_EquityMethodInvestmentSummarizedFinancialInformationRevenue / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember | 7,316,000 us-gaap_EquityMethodInvestmentSummarizedFinancialInformationRevenue / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember |
Property operating expenses |  |  |  |  | (2,818,000)ofc_EquityMethodInvestmentSummarizedFinancialInformationPropertyOperatingExpenses / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember | (2,829,000)ofc_EquityMethodInvestmentSummarizedFinancialInformationPropertyOperatingExpenses / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember |
Interest expense |  |  |  |  | (10,463,000)ofc_EquityMethodInvestmentSummarizedFinancialInformationInterestExpenses / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember | (7,672,000)ofc_EquityMethodInvestmentSummarizedFinancialInformationInterestExpenses / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember |
Depreciation and amortization expense |  |  |  |  | (2,067,000)ofc_EquityMethodInvestmentSummarizedFinancialInformationDepreciationAndAmortizationExpenses / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember | (2,283,000)ofc_EquityMethodInvestmentSummarizedFinancialInformationDepreciationAndAmortizationExpenses / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember |
Gain on early extinguishment of debt |  |  |  |  | 23,013,000 ofc_EquityMethodInvestmentSummarizedFinancialInformationGainsLossesonExtinguishmentofDebt / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember | 0 ofc_EquityMethodInvestmentSummarizedFinancialInformationGainsLossesonExtinguishmentofDebt / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember |
Net income (loss) |  |  |  |  | 14,184,000 us-gaap_EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLoss / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember | (5,468,000)us-gaap_EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLoss / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember |
Unconsolidated real estate joint ventures | Nonrecourse loan guarantees of unconsolidated partnership | Nonrecourse mezzanine loan |  |  |  |  |  |  |
Investments in consolidated real estate joint ventures |  |  |  |  |  |  |
Nonrecourse mezzanine debt balance, equity method joint venture | 5,600,000 ofc_NonrecourseMezzanineDebtBalanceequitymethodjointventure / dei_LegalEntityAxis = us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember / us-gaap_LongtermDebtTypeAxis = ofc_NonrecourseMezzanineLoanMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = ofc_NonrecourseLoanGuaranteesofUnconsolidatedPartnershipMember |  |  |  |  |  |
LW Redstone Company, LLC | Variable Interest Entity, Primary Beneficiary |  |  |  |  |  |  |
Investments in consolidated real estate joint ventures |  |  |  |  |  |  |
Ownership (as a percent) | 85.00%us-gaap_VariableInterestEntityOwnershipPercentage / us-gaap_CounterpartyNameAxis = ofc_LwRedstoneCompanyLlcMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember |  |  |  |  |  |
Total Assets | 143,534,000 us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets / us-gaap_CounterpartyNameAxis = ofc_LwRedstoneCompanyLlcMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | [1],[2] |  |  |  |  |
Encumbered Assets | 66,620,000 us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate / us-gaap_CounterpartyNameAxis = ofc_LwRedstoneCompanyLlcMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | [1],[2] |  |  |  |  |
Total Liabilities | 41,659,000 us-gaap_VariableInterestEntityConsolidatedCarryingAmountLiabilities / us-gaap_CounterpartyNameAxis = ofc_LwRedstoneCompanyLlcMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | [1],[2] |  |  |  |  |
M Square Associates, LLC | Variable Interest Entity, Primary Beneficiary |  |  |  |  |  |  |
Investments in consolidated real estate joint ventures |  |  |  |  |  |  |
Ownership (as a percent) | 50.00%us-gaap_VariableInterestEntityOwnershipPercentage / us-gaap_CounterpartyNameAxis = ofc_MSquareAssociatesLlcMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember |  |  |  |  |  |
Total Assets | 59,414,000 us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets / us-gaap_CounterpartyNameAxis = ofc_MSquareAssociatesLlcMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | [1],[3] |  |  |  |  |
Encumbered Assets | 48,856,000 us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate / us-gaap_CounterpartyNameAxis = ofc_MSquareAssociatesLlcMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | [1],[3] |  |  |  |  |
Total Liabilities | 39,077,000 us-gaap_VariableInterestEntityConsolidatedCarryingAmountLiabilities / us-gaap_CounterpartyNameAxis = ofc_MSquareAssociatesLlcMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | [1],[3] |  |  |  |  |
COPT-FD Indian Head, LLC | Variable Interest Entity, Primary Beneficiary |  |  |  |  |  |  |
Investments in consolidated real estate joint ventures |  |  |  |  |  |  |
Proceeds from real estate and real estate joint ventures |  |  |  |  |  |  | 6,400,000 us-gaap_ProceedsFromRealEstateAndRealEstateJointVentures / us-gaap_CounterpartyNameAxis = ofc_CoptFdIndianHeadLlcMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Notes receivable from City of Huntsville |  |  |  |  |  |  |
Investments in consolidated real estate joint ventures |  |  |  |  |  |  |
Investing receivables | $ 49,147,000 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ofc_NotesReceivableFromCityOfHuntsvilleMember |  |  |  | $ 44,055,000 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = ofc_NotesReceivableFromCityOfHuntsvilleMember |  |
[1] | Excludes amounts eliminated in consolidation.
[2] | This joint venture’s property is in Huntsville, Alabama.
[3] | This joint venture’s properties are in College Park, Maryland (in the Baltimore/Washington Corridor).

X
- Definition Number of buildings operated by the joint ventures. + References No definition available. + Details
Name: | ofc_BuildingsOperatedByJointVenturesNumber
Namespace Prefix: | ofc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | ofc_ConsolidatedJointVenturesDisclosureAbstract
Namespace Prefix: | ofc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents a defined threshold for square footage of construction commencement for Company to be able to acquire partner's interest after five years. + References No definition available. + Details
Name: | ofc_ConstructionCommencementThreshold
Namespace Prefix: | ofc_
Data Type: | num:areaItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents a completed threshold for square footage of construction commencement for Company to be able to acquire partner's interest after five years. + References No definition available. + Details
Name: | ofc_ConstructionCommencementThresholdCompleted
Namespace Prefix: | ofc_
Data Type: | num:areaItemType
Balance Type: | na
Period Type: | duration

X
- Definition Carrying value as of balance sheet date of investments in the following types of entities when distributions received on such investments exceed amounts invested: (A) an entity in which the entity has significant influence, but does not have control, (B) subsidiaries that are not required to be consolidated and are accounted for using the equity and or cost method, and (C) an entity in which the reporting entity shares control of the entity with another party or group. Includes long-term advances receivable from or payable to such an entity and adjustments for other than temporary impairment losses recognized. + References No definition available. + Details
Name: | ofc_DistributionsReceivedInExcessOfInvestmentInUnconsolidatedRealEstateJointVenture
Namespace Prefix: | ofc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of depreciation and amortization expense reported by an equity method investment of the entity. + References No definition available. + Details
Name: | ofc_EquityMethodInvestmentSummarizedFinancialInformationDepreciationAndAmortizationExpenses
Namespace Prefix: | ofc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Equity Method Investment, Summarized Financial Information, Gains (Losses) on Extinguishment of Debt + References No definition available. + Details
Name: | ofc_EquityMethodInvestmentSummarizedFinancialInformationGainsLossesonExtinguishmentofDebt
Namespace Prefix: | ofc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of interest and debt related expenses associated with nonoperating financing activities reported by an equity method investment of the entity. + References No definition available. + Details
Name: | ofc_EquityMethodInvestmentSummarizedFinancialInformationInterestExpenses
Namespace Prefix: | ofc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of costs incurred that are directly related to generating revenues from leased and rented property or equipment reported by an equity method investment of the entity. + References No definition available. + Details
Name: | ofc_EquityMethodInvestmentSummarizedFinancialInformationPropertyOperatingExpenses
Namespace Prefix: | ofc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents infrastructure costs anticipated to be funded by entity for reimbursement. + References No definition available. + Details
Name: | ofc_InfrastructureCostsAnticipatedToBeFunded
Namespace Prefix: | ofc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents the balance of nonrecourse mezzanine debt of unconsolidated real estate joint venture. + References No definition available. + Details
Name: | ofc_NonrecourseMezzanineDebtBalanceequitymethodjointventure
Namespace Prefix: | ofc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Number of years following construction commencement threshold achievement before partner's interest can be purchased at fair value + References No definition available. + Details
Name: | ofc_NumberOfYearsFollowingConstructionCommencementThresholdAchievementBeforePartnersInterestCanBePurchasedAtFairValue
Namespace Prefix: | ofc_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the amount credited to the partner's capital upon formation. + References No definition available. + Details
Name: | ofc_PartnersCapitalAccountUponFormation
Namespace Prefix: | ofc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Represents the percentage of residual distributable cash flows in excess of unpaid cumulative preferred returns and return of invested capital in the joint venture to which the entity will be entitled. + References No definition available. + Details
Name: | ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCapital
Namespace Prefix: | ofc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the percentage of residual distributable cash flowsin excess of unpaid cumulative preferred turns and return of invested cash in the joint venture to which the entity's partners will be entitled. + References No definition available. + Details
Name: | ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCashRelatedToRealEstatePartner
Namespace Prefix: | ofc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the percentage in which the residual net cash flows will be distributed to each partner. + References No definition available. + Details
Name: | ofc_PercentageOfResidualNetCashFlowDistributedToEachPartner
Namespace Prefix: | ofc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Difference between amount at which an investment accounted for under the equity method of accounting is carried (reported) on the balance sheet and amount of underlying equity in net assets the reporting Entity has in the investee. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of gain (loss) on sale or disposal of an equity method investment. + References No definition available. + Details
Name: | us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

X
- Definition The amount of net income (loss) reported by an equity method investment of the entity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(g)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33912-111571 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 28 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph bb -Article 1 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph g -Subparagraph 1, 2 -Article 4 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph w -Article 1 + Details
Name: | us-gaap_EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of revenue from sale of goods and services reduced by sales returns, allowances, and discounts reported by an equity method investment of the entity. + References No definition available. + Details
Name: | us-gaap_EquityMethodInvestmentSummarizedFinancialInformationRevenue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.3) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 3 -Article 5 + Details
Name: | us-gaap_NotesReceivableNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The carrying amount, as of the date of the latest financial statement presented, of real estate owned but transferred to serve as collateral for the payment of the related debt obligation, primarily a secured borrowing or repurchase agreement, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (b)(1)(i) -URI http://asc.fasb.org/extlink&oid=34720971&loc=SL6224234-111729 + Details
Name: | us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The cash inflow from the sale of real estate held-for-investment and real estate joint ventures. + References No definition available. + Details
Name: | us-gaap_ProceedsFromRealEstateAndRealEstateJointVentures
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Number of shares of stock issued during the period pursuant to acquisitions. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.28,29) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30 -Article 5 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesAcquisitions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Value of stock issued pursuant to acquisitions during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.29-31) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30, 31 -Article 5 + Details
Name: | us-gaap_StockIssuedDuringPeriodValueAcquisitions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The carrying amount of the consolidated Variable Interest Entity's assets included in the reporting entity's statement of financial position. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (bb) -URI http://asc.fasb.org/extlink&oid=28200181&loc=d3e5710-111685 + Details
Name: | us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The carrying amount of the consolidated Variable Interest Entity's liabilities included in the reporting entity's statement of financial position. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (bb) -URI http://asc.fasb.org/extlink&oid=28200181&loc=d3e5710-111685 + Details
Name: | us-gaap_VariableInterestEntityConsolidatedCarryingAmountLiabilities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 5A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=28200181&loc=SL6759159-111685 + Details
Name: | us-gaap_VariableInterestEntityOwnershipPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=ofc_ArundelPreserveLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=ofc_LwRedstoneCompanyLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=ofc_MorForbes2LlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=ofc_MSquareAssociatesLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=us-gaap_VariableInterestEntityPrimaryBeneficiaryAggregatedDisclosureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=ofc_NotesReceivableFromCityOfHuntsvilleMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CounterpartyNameAxis=ofc_CoptFdIndianHeadLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CounterpartyNameAxis=ofc_LwRedstoneCompanyLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CounterpartyNameAxis=ofc_MSquareAssociatesLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |