XML 74 R49.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Organization (Details 2) | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016
Corporate Office Properties, L.P. [Member] | Common Units [Member] |  |
Forms of ownership in Operating Partnership and ownership percentage by the entity |  |
Percentage ownership in operating partnership | 96.90% | 96.50%

X
- Definition Line items related to the percentage of classes of ownership in a subsidiary that are owned by the parent. + References No definition available. + Details
Name: | ofc_OwnershipInSubsidiaryPercentageLineItems
Namespace Prefix: | ofc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- 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

X
- Details
Name: | us-gaap_ConsolidatedEntitiesAxis=us-gaap_SubsidiariesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ofc_UnitsByNameAxis=ofc_CommonUnitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |