Annual report pursuant to Section 13 and 15(d)

Shareholders' Equity (Details)

v2.4.0.6
Shareholders' Equity (Details) (USD $)
 1 Months Ended 3 Months Ended 12 Months Ended
May 31, 2011
Nov. 30, 2010
Dec. 31, 2011
Sep. 30, 2011
Jun. 30, 2011
Mar. 31, 2011
Dec. 31, 2010
Sep. 30, 2010
Jun. 30, 2010
Mar. 31, 2010
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Preferred Shares                          
Aggregate Liquidation Preference     $ 216,333,000       $ 216,333,000       $ 216,333,000 $ 216,333,000  
Common Shares                          
Common shares issued to the public (in shares) 4,600,000 7,475,000                 4,600,000 7,475,000 2,990,000
Per share value of common shares issued to the public (in dollars per share) $ 33.00 $ 34.25                      
Net proceeds from issue of shares after underwriter discounts but before offering expenses 145,700,000 245,800,000                      
Number of operating partnership units converted into common shares (in units)                     100,939 663,498 2,841,394
Number of common shares for each converted common unit (in shares)                     1    
Dividends declared per common share (in dollars per share)                     $ 1.65 $ 1.61 $ 1.53
Accumulated other comprehensive loss activity                          
Beginning balance           (4,163,000)       (1,907,000) (4,163,000) (1,907,000) (4,749,000)
Amount of loss recognized in AOCL (effective portion)                     (31,531,000) (5,473,000) (3,253,000)
Amount of loss reclassified from AOCL to income (effective portion)                     4,601,000 3,689,000 6,680,000
Amount of loss reclassified from AOCL to loss on interest rate derivatives upon discontinuing hedge accounting                     28,430,000    
Adjustment to AOCL attributable to noncontrolling interests                     930,000 (472,000) (585,000)
Ending balance     (1,733,000)       (4,163,000)       (1,733,000) (4,163,000) (1,907,000)
Comprehensive income                          
Net (loss) income     (87,215,000) 7,470,000 (26,007,000) (18,566,000) 16,752,000 8,926,000 9,151,000 10,675,000 (124,318,000) 45,504,000 61,299,000
Amount of loss recognized in AOCL                     (31,531,000) (5,473,000) (3,253,000)
Amount of loss reclassified from AOCL to income (effective portion)                     4,601,000 3,689,000 6,680,000
Amount of loss reclassified from AOCL to loss on interest rate derivatives upon discontinuing hedge accounting                     28,430,000    
Total comprehensive (loss) income                     (122,818,000) 43,720,000 64,726,000
Net loss (income) attributable to noncontrolling interests     4,988,000 (904,000) 1,783,000 776,000 (1,228,000) (94,000) (685,000) (737,000) 6,643,000 (2,744,000) (4,970,000)
Other comprehensive loss (income) attributable to noncontrolling interests                     (16,000) 153,000 (349,000)
Total comprehensive (loss) income attributable to COPT                     (116,191,000) 41,129,000 59,407,000
Preferred Shares
                          
Preferred Shares                          
Number of shares issued     8,121,667               8,121,667    
Number of preferred shares of beneficial interest authorized (in shares)     15,000,000               15,000,000    
Par value of preferred shares of beneficial interest authorized (in dollars per share)     $ 0.01               $ 0.01    
Series G
                          
Preferred Shares                          
Number of shares issued     2,200,000               2,200,000    
Aggregate Liquidation Preference     55,000,000               55,000,000    
Annual Dividend Yield                     8.00%    
Annual Dividend Per Share (in dollars per share)                     $ 2.00000    
Series H
                          
Preferred Shares                          
Number of shares issued     2,000,000               2,000,000    
Aggregate Liquidation Preference     50,000,000               50,000,000    
Annual Dividend Yield                     7.50%    
Annual Dividend Per Share (in dollars per share)                     $ 1.87500    
Series J
                          
Preferred Shares                          
Number of shares issued     3,390,000               3,390,000    
Aggregate Liquidation Preference     84,750,000               84,750,000    
Annual Dividend Yield                     7.625%    
Annual Dividend Per Share (in dollars per share)                     $ 1.90625    
Series K
                          
Preferred Shares                          
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