Annual report pursuant to Section 13 and 15(d)

Earnings Per Share ("EPS") and Earnings Per Unit (???EPU???) (Details 2)

v3.6.0.2
Earnings Per Share ("EPS") and Earnings Per Unit (“EPU”) (Details 2) - shares
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Conversion of common units [Member]      
Antidilutive securities      
Weighted average antidilutive securities excluded from computation of diluted earnings per share (in shares) 3,633,000 0 3,897,000
Conversion of Series I preferred units [Member]      
Antidilutive securities      
Weighted average antidilutive securities excluded from computation of diluted earnings per share (in shares) 176,000 176,000 176,000
Conversion of Series K preferred shares [Member]      
Antidilutive securities      
Weighted average antidilutive securities excluded from computation of diluted earnings per share (in shares) 434,000 434,000 434,000
Restricted Stock and Deferred Shares [Member]      
Antidilutive securities      
Weighted average antidilutive securities excluded from computation of diluted earnings per share (in shares) 385,000 410,000 401,000
Stock Options [Member]      
Antidilutive securities      
Weighted average antidilutive securities excluded from computation of diluted earnings per share (in shares) 285,000 469,000 492,000
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) 176,000 176,000 176,000
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) 385,000 410,000 401,000
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) 285,000 469,000 492,000
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) 434,000 434,000 434,000