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Summary of Significant Accounting Policies (Details 1)
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12 Months Ended |
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Dec. 31, 2014
Form
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| Cash and Cash Equivalents | |
| Maximum term until original maturity to classify cash and liquid investments as cash and cash equivalent (in months) | 3 months |
| Share-Based Compensation | |
| Number of forms of share based compensation plans | 2ofc_NumberofDifferentFormsofShareBasedCompensation |
| Market concentration premium | |
| Useful Lifes Related To Intangible Assets and Property [Abstract] | |
| Finite-Lived Intangible Asset, Useful Life | 40 years |
| Corporate Office Properties, L.P. | |
| Noncontrolling Interest [Abstract] | |
| Interests in several real estate entities owned directly by COPT |
1.00%ofc_NoncontrollingInterestPercentageGenerallyOwnedbyParent / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |
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- Definition
Represents the maximum term until original maturity to classify cash and liquid investments as cash and cash equivalents. No definition available.
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Percentage of ownership in noncontrolling interests generally not exceeded by Parent. No definition available.
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Number of Different Forms of Share Based Compensation No definition available.
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- Definition
Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. No definition available.
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