Annual report pursuant to Section 13 and 15(d)

Equity - COPLP and Subsidiaries (Details)

v2.4.0.8
Equity - COPLP and Subsidiaries (Details) (USD $)
 0 Months Ended 1 Months Ended 12 Months Ended 0 Months Ended 12 Months Ended 0 Months Ended 12 Months Ended 0 Months Ended 12 Months Ended 0 Months Ended 12 Months Ended 0 Months Ended 1 Months Ended 12 Months Ended
Mar. 19, 2013
Oct. 31, 2012
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Jul. 16, 2013
Common Stock Issued to Public Under At-the-Market Program
Jun. 27, 2012
Series L Preferred Units
Public Offering
Aug. 06, 2012
Series G Preferred Shares
Dec. 31, 2013
Preferred Shares
Dec. 31, 2012
Preferred Shares
Dec. 31, 2013
Series H
Dec. 31, 2013
Series K
Dec. 31, 2013
Series L Cumulative Preferred Stock
Jun. 27, 2012
Series L Cumulative Preferred Stock
Public Offering
Apr. 22, 2013
Series J
Dec. 31, 2013
Common Shares
Dec. 31, 2012
Common Shares
Dec. 31, 2011
Common Shares
Dec. 31, 2013
Corporate Office Properties, L.P.
Dec. 31, 2012
Corporate Office Properties, L.P.
Dec. 31, 2011
Corporate Office Properties, L.P.
Jul. 16, 2013
Corporate Office Properties, L.P.
Common Stock Issued to Public Under At-the-Market Program
Dec. 31, 2013
Corporate Office Properties, L.P.
Common Units
Trustee
Dec. 31, 2012
Corporate Office Properties, L.P.
Common Units
Dec. 31, 2013
Corporate Office Properties, L.P.
Conversion of Series I preferred units
Jun. 27, 2012
Corporate Office Properties, L.P.
Series L Preferred Units
Public Offering
Aug. 06, 2012
Corporate Office Properties, L.P.
Series G Preferred Shares
Dec. 31, 2012
Corporate Office Properties, L.P.
Preferred Shares
Dec. 31, 2013
Corporate Office Properties, L.P.
Series H
Dec. 31, 2013
Corporate Office Properties, L.P.
Series K
Dec. 31, 2013
Corporate Office Properties, L.P.
Series L Cumulative Preferred Stock
Jun. 27, 2012
Corporate Office Properties, L.P.
Series L Cumulative Preferred Stock
Public Offering
Apr. 22, 2013
Corporate Office Properties, L.P.
Series J
Mar. 31, 2013
Corporate Office Properties, L.P.
Common Shares
Oct. 31, 2012
Corporate Office Properties, L.P.
Common Shares
Dec. 31, 2012
Corporate Office Properties, L.P.
Common Shares
Preferred Stock                                                                        
Number of shares issued     9,431,667               2,000,000 531,667 6,900,000           9,431,667                   2,000,000 531,667 6,900,000          
Aggregate Liquidation Preference     $ 249,083,000 $ 333,833,000             $ 50,000,000 $ 26,583,000 $ 172,500,000           $ 249,083,000                   $ 50,000,000 $ 26,583,000 $ 172,500,000          
Annual dividend yield               8.00%     7.50% 5.60% 7.375%   7.625%                   7.50%   8.00%   7.50% 5.60% 7.375%   7.625%      
Annual dividend per share (in dollars per share)                     $ 1.87500 $ 2.80000 $ 1.84375                               $ 1.87500 $ 2.80000 $ 1.84375          
Number of common shares to be issued on conversion of each preferred share                       0.8163                                   0.8163            
Net proceeds from issuance of Series L preferred shares     0 165,652,000 0                 165,700,000         0 165,652,000 0                     165,700,000        
Number of Series L preferred units of operating partnerships received in exchange for offering proceeds (in units)             6,900,000                                     6,900,000                    
Preferred stock, redemption price per share               $ 25             $ 25                       $ 25           $ 25      
Stock redeemed or called during period (in units/ shares)     84,750,000 55,000,000       55,000,000             84,800,000       84,750,000 55,000,000             55,000,000           84,800,000      
Issuance costs associated with redeemed preferred shares               1,800,000             2,900,000                       1,800,000           2,900,000      
Annual Cumulative Preferred Return Increment Frequency                                                 5 years                      
Common Shares                                                                        
Shares issued to the public 4,485,000 8,600,000     4,600,000 1,500,000        6,900,000       6,900,000   4,485,000 8,625,000 4,600,000       1,500,000                   6,900,000   4,485,000.000 8,600,000.0  
Per share value of common and preferred shares issued to the public (in dollars per share) $ 26.34 $ 24.75                       $ 25.00                                   $ 25.00   $ 26.34 $ 24.75  
Net proceeds from issue of shares after underwriter discounts but before offering expenses 118,100,000 204,900,000 117,961,000   145,367,000 38,500,000       165,652,000             204,696,000   117,961,000   145,367,000 38,500,000           165,652,000           118,100,000 204,900,000 204,696,000
Issuance of stock, weighted average price per share           $ 26.05                               $ 26.05                            
Payments of stock issuance costs           586,000                               586,000                            
Number of common shares for each converted common unit (in shares)     1                               1                                  
Number of operating partnerships units converted into common shares (in units)     311,343 234,246 100,939                           311,343.000 234,246.000                                
Dividends declared per common share     $ 1.1000 $ 1.1 $ 1.65                           $ 1.1 $ 1.1 $ 1.65                              
Limited Partners' Capital Account, Units Issued                                                 352,000                      
Preferred units in COPLP     $ 8,800,000 $ 8,800,000                                         $ 8,800,000                      
Preferred Stock, Liquidation Preference Per Share                                                 $ 25.00                      
Common Units Conversion Basis Units Issuable                                                 0.5                      
Percentage ownership in operating partnership                                             95.60% 95.20%                        
Number of trustees controlling additional common units                                             3                          
Additional percentage of common units controlled by trustees (as a percent)                                             3.40%