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Earnings Per Share ("EPS") and Earnings Per Unit (“EPU”) (Details 2) - shares shares in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Conversion of common units [Member] |  |  |
Antidilutive securities |  |  |
Weighted average antidilutive securities excluded from computation of diluted earnings per share (in shares) | 3,362 | 3,633 | 0
Conversion of Series I preferred units [Member] |  |  |
Antidilutive securities |  |  |
Weighted average antidilutive securities excluded from computation of diluted earnings per share (in shares) | 176 | 176 | 176
Conversion of Series K preferred shares [Member] |  |  |
Antidilutive securities |  |  |
Weighted average antidilutive securities excluded from computation of diluted earnings per share (in shares) | 0 | 434 | 434
Restricted Stock and Deferred Shares [Member] |  |  |
Antidilutive securities |  |  |
Weighted average antidilutive securities excluded from computation of diluted earnings per share (in shares) | 433 | 385 | 410
Stock Options [Member] |  |  |
Antidilutive securities |  |  |
Weighted average antidilutive securities excluded from computation of diluted earnings per share (in shares) | 70 | 285 | 469
Corporate Office Properties, L.P. [Member] | Restricted Stock and Deferred Shares [Member] |  |  |
Antidilutive securities |  |  |
Weighted average antidilutive securities excluded from computation of diluted earnings per share (in shares) | 433 | 385 | 410
Corporate Office Properties, L.P. [Member] | Stock Options [Member] |  |  |
Antidilutive securities |  |  |
Weighted average antidilutive securities excluded from computation of diluted earnings per share (in shares) | 70 | 285 | 469
Corporate Office Properties, L.P. [Member] | Conversion of Series I preferred units [Member] |  |  |
Antidilutive securities |  |  |
Weighted average antidilutive securities excluded from computation of diluted earnings per share (in shares) | 176 | 176 | 176
Corporate Office Properties, L.P. [Member] | Conversion of Series K preferred units [Member] |  |  |
Antidilutive securities |  |  |
Weighted average antidilutive securities excluded from computation of diluted earnings per share (in shares) | 0 | 434 | 434

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- Definition Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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