Annual report pursuant to Section 13 and 15(d)

Equity - COPLP and Subsidiaries (Details)

v3.6.0.2
Equity - COPLP and Subsidiaries (Details) - USD ($)
 1 Months Ended 3 Months Ended 12 Months Ended
Jun. 16, 2014
Nov. 30, 2014
Dec. 31, 2016
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Preferred Stock            
Number of shares issued     7,431,667 7,431,667    
Aggregate liquidation preference     $ 199,083,000 $ 199,083,000    
Stock redeemed or called during period value       $ 26,583,000   $ 50,000,000
Common Shares            
Shares issued to the public   5,520,000        
Per share value of common and preferred shares issued to the public (in dollars per share)   $ 27.30        
Net proceeds from issue of shares after underwriter discounts but before offering expenses   $ 148,900,000       $ 148,666,000
Number of common shares for each converted common unit (in shares)       1    
Number of operating partnerships units converted into common shares (in units)       87,000 160,160 140,149
Dividends declared per common share (in dollars per share)       $ 1.1 $ 1.10 $ 1.10
Preferred units in COPLP     $ 8,800,000 $ 8,800,000 $ 8,800,000  
Common Stock Issued to Public Under At-the-Market Program [Member]            
Common Shares            
Shares issued to the public     3,721,227 3,721,227 890,241 0
Issuance of stock, weighted average price per share (in dollars per share)     $ 29.56   $ 30.29  
Payments of stock issuance costs     $ 900,000   $ 400,000  
Series H [Member]            
Preferred Stock            
Annual dividend yield 7.50%          
Preferred stock, redemption price per share (in dollars per share) $ 25          
Stock redeemed or called during period value $ 50,000,000          
Issuance costs associated with redeemed preferred shares $ 1,800,000          
Series K [Member]            
Preferred Stock            
Number of shares issued     531,667 531,667    
Aggregate liquidation preference     $ 26,583,000 $ 26,583,000    
Annual dividend yield       5.60%    
Annual dividend per share (in dollars per share)       $ 2.80000    
Number of common shares to be issued on conversion of each preferred share     0.8163 0.8163    
Issuance costs associated with redeemed preferred shares       $ 17,000    
Series L [Member]            
Preferred Stock            
Number of shares issued     6,900,000 6,900,000    
Aggregate liquidation preference     $ 172,500,000 $ 172,500,000    
Annual dividend yield       7.375%    
Annual dividend per share (in dollars per share)       $ 1.84375    
Corporate Office Properties, L.P. [Member]            
Preferred Stock            
Number of shares issued     7,431,667 7,431,667    
Aggregate liquidation preference     $ 199,083,000 $ 199,083,000    
Stock redeemed or called during period value       $ (26,583,000)   $ 50,000,000
Common Shares            
Net proceeds from issue of shares after underwriter discounts but before offering expenses           $ 148,666,000
Number of common shares for each converted common unit (in shares)       1    
Number of operating partnerships units converted into common shares (in units)       87,000 160,160.00 140,149.000
Dividends declared per common share (in dollars per share)       $ 1.1 $ 1.10 $ 1.10
Corporate Office Properties, L.P. [Member] | Common Stock Issued to Public Under At-the-Market Program [Member]            
Common Shares            
Shares issued to the public       3,721,227.000 890,241  
Net proceeds from issue of shares after underwriter discounts but before offering expenses       $ 109,100,000 $ 26,600,000  
Issuance of stock, weighted average price per share (in dollars per share)       $ 29.56 $ 30.29  
Payments of stock issuance costs       $ 900,000 $ 400,000  
Corporate Office Properties, L.P. [Member] | Common Units [Member]            
Common Shares            
Percentage ownership in operating partnership       96.50% 96.30%  
Corporate Office Properties, L.P. [Member] | Conversion of Series I preferred units [Member]            
Preferred Stock            
Annual dividend yield       7.50%    
Annual cumulative preferred return increment frequency       5 years    
Common Shares            
Limited partners' capital account, units issued     352,000 352,000    
Preferred units in COPLP     $ 8,800,000 $ 8,800,000    
Preferred stock, liquidation preference per share     $ 25 $ 25    
Common units conversion basis units issuable       0.5    
Corporate Office Properties, L.P. [Member] | Series H [Member]            
Preferred Stock            
Annual dividend yield 7.50%          
Preferred stock, redemption price per share (in dollars per share) $ 25          
Stock redeemed or called during period value $ 50,000,000          
Issuance costs associated with redeemed preferred shares $ 1,800,000          
Corporate Office Properties, L.P. [Member] | Series K [Member]            
Preferred Stock            
Number of shares issued     531,667 531,667    
Aggregate liquidation preference     $ 26,583,000 $ 26,583,000    
Annual dividend yield       5.60%    
Annual dividend per share (in dollars per share)       $ 2.80000    
Number of common shares to be issued on conversion of each preferred share     0.8163 0.8163    
Issuance costs associated with redeemed preferred shares       $ 17,000    
Corporate Office Properties, L.P. [Member] | Series L [Member]            
Preferred Stock            
Number of shares issued     6,900,000 6,900,000    
Aggregate liquidation preference     $ 172,500,000 $ 172,500,000    
Annual dividend yield       7.375%    
Annual dividend per share (in dollars per share)       $ 1.84375    
Corporate Office Properties, L.P. [Member] | Common Shares [Member]            
Common Shares            
Shares issued to the public   5,520,000        
Per share value of common and preferred shares issued to the public (in dollars per share)   $ 27.30        
Net proceeds from issue of shares after underwriter discounts but before offering expenses   $ 148,900,000