Quarterly report [Sections 13 or 15(d)]

Organization (Details)

v3.26.3
Organization (Details) - 9 months ended Sep. 30, 2026
ft² in Millions
property
ft²
a
shares
Preferred Units        
Investments in real estate        
Limited partners' capital account, units outstanding (in units) | shares       0
COPT Defense Properties, L.P. | Common Units | COPT Defense Properties        
Investments in real estate        
Percentage ownership in operating partnership 97.20%      
Unconsolidated Real Estate Joint Ventures        
Investments in real estate        
Number of real estate properties 24      
Operating Properties | Defense/IT Portfolio        
Investments in real estate        
Number of real estate properties 202      
Area of real estate property (in sqft or acres) | ft²   23.3    
Operating Properties | Defense/IT Portfolio | Unconsolidated Real Estate Joint Ventures        
Investments in real estate        
Number of real estate properties 24      
Area of real estate property (in sqft or acres) | ft²   4.3    
Operating Properties | Other | Greater Washington, DC/Baltimore        
Investments in real estate        
Number of real estate properties 6      
Area of real estate property (in sqft or acres) | ft²   2.0    
Properties under development | Defense/IT Portfolio        
Investments in real estate        
Number of real estate properties 8      
Area of real estate property (in sqft or acres) | ft²   1.1    
Land controlled for development | Greater Washington, DC/Baltimore        
Investments in real estate        
Area of real estate property (in sqft or acres) | a     10  
Land controlled for development | Defense/IT Portfolio        
Investments in real estate        
Area of real estate property (in sqft or acres)   10.4 930