Earnings Per Share ("EPS") and Earnings Per Unit ("EPU") (Details 2)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Conversion of common units    
Antidilutive securities    
Antidilutive securities excluded from computation of diluted earnings per share (in shares) 3,732 3,958
Conversion of Series I Preferred Units    
Antidilutive securities    
Antidilutive securities excluded from computation of diluted earnings per share (in shares) 176 176
Conversion of Series K Preferred Shares    
Antidilutive securities    
Antidilutive securities excluded from computation of diluted earnings per share (in shares) 434 434
Weighted average restricted shares    
Antidilutive securities    
Antidilutive securities excluded from computation of diluted earnings per share (in shares) 400 390
Weighted average options    
Antidilutive securities    
Antidilutive securities excluded from computation of diluted earnings per share (in shares) 474 588
Corporate Office Properties, L.P. | Weighted average restricted shares    
Antidilutive securities    
Antidilutive securities excluded from computation of diluted earnings per share (in shares) 400 390
Corporate Office Properties, L.P. | Weighted average options    
Antidilutive securities    
Antidilutive securities excluded from computation of diluted earnings per share (in shares) 474 588
Corporate Office Properties, L.P. | Conversion of Series I preferred units    
Antidilutive securities    
Antidilutive securities excluded from computation of diluted earnings per share (in shares) 176 176
Corporate Office Properties, L.P. | Conversion of Series K preferred units    
Antidilutive securities    
Antidilutive securities excluded from computation of diluted earnings per share (in shares) 434 434