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Organization (Details 2) (Corporate Office Properties, L.P.) | 9 Months Ended
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Sep. 30, 2013 Trustee
Common Units |
Forms of ownership in Operating Partnership and ownership percentage by the entity |
Percentage ownership in operating partnership | 95.60%
Number of trustees controlling additional common units | 3
Additional percentage of common units controlled by trustees (as a percent) | 3.40%
Preferred Units |
Forms of ownership in Operating Partnership and ownership percentage by the entity |
Percentage ownership in operating partnership | 96.40%

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- Definition Additional percentage of the operating partnership's common units controlled by trustees, either directly or through ownership by other entities or family members. + References No definition available. + Details
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Namespace Prefix: | ofc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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- Definition Represents the number of trustees who control common units in addition to those owned by the entity. + References No definition available. + Details
Name: | ofc_NumberOfTrusteesControllingAdditionalCommonUnits
Namespace Prefix: | ofc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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

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- Definition Percentage investment held by the managing member or general partner of the limited liability company (LLC) or limited partnership (LP). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 272 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055 + Details
Name: | us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration