Annual report pursuant to Section 13 and 15(d)

Properties, net (Details 4)

v3.3.1.900
Properties, net (Details 4)
$ / shares in Units, ft² in Thousands, $ in Thousands
 12 Months Ended
Aug. 07, 2015
USD ($)
ft²
Apr. 15, 2015
USD ($)
ft²
Mar. 19, 2015
USD ($)
ft²
Dec. 31, 2015
USD ($)
$ / shares
Dec. 31, 2014
USD ($)
$ / shares
Business Combination          
Weighted average amortization period of intangible assets       11 years  
Pro Forma Information          
Pro forma total revenues       $ 641,982 $ 623,013
Pro forma net income attributable to COPT common shareholders       $ 167,079 $ 20,796
Pro Forma EPS Basic (in dollars per share) | $ / shares       $ 1.77 $ 0.23
Pro Forma EPS Diluted (in dollars per share) | $ / shares       $ 1.77 $ 0.23
Tenant relationship value [Member]          
Business Combination          
Weighted average amortization period of intangible assets       11 years  
Below-market cost arrangements [Member]          
Business Combination          
Weighted average amortization period of intangible assets       35 years  
250 W Pratt St [Member] | Baltimore, Maryland [Member]          
Business Acquisition [Line Items]          
Square footage of real estate properties (in square feet) | ft²     367    
Acquired property percentage leased     96.20%    
Payments to acquire real estate     $ 61,800    
2600 Park Tower Drive [Member] | Vienna, Virginia [Member]          
Business Acquisition [Line Items]          
Square footage of real estate properties (in square feet) | ft²   237      
Acquired property percentage leased   100.00%      
Payments to acquire real estate   $ 80,500      
100 and 30 Light Street [Member] | Baltimore, Maryland [Member]          
Business Acquisition [Line Items]          
Square footage of real estate properties (in square feet) | ft² 558        
Acquired property percentage leased 93.50%        
Payments to acquire real estate $ 121,200        
Liabilities incurred 55,000        
Fair value assumption of debt $ 55,500        
2015 Property Acquisitions [Member]          
Business Combination          
Land, operating properties       $ 55,076  
Building and improvements       139,540  
Intangible assets on real estate acquisitions       75,729  
Total assets       270,345  
Below-market leases       (6,808)  
Total acquisition cost       263,537  
Finite-lived Intangible Assets Acquired       $ 75,729  
Weighted average amortization period of intangible assets       10 years  
Contributed revenues       $ 20,200  
Net income from continuing operations since acquisition date       1,200  
Acquisition related costs       4,100  
2015 Property Acquisitions [Member] | Tenant relationship value [Member]          
Business Combination          
Finite-lived Intangible Assets Acquired       $ 31,183  
Weighted average amortization period of intangible assets       12 years  
2015 Property Acquisitions [Member] | Leases, Acquired-in-Place [Member]          
Business Combination          
Finite-lived Intangible Assets Acquired       $ 35,139  
Weighted average amortization period of intangible assets       7 years  
2015 Property Acquisitions [Member] | Above Market Leases [Member]          
Business Combination          
Finite-lived Intangible Assets Acquired       $ 6,720  
Weighted average amortization period of intangible assets       4 years  
2015 Property Acquisitions [Member] | Below-market cost arrangements [Member]          
Business Combination          
Finite-lived Intangible Assets Acquired       $ 2,687  
Weighted average amortization period of intangible assets       40 years