Annual report pursuant to Section 13 and 15(d)

Organization (Narrative) (Details)

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Organization (Narrative) (Details) - 12 months ended Dec. 31, 2021
ft² in Millions
property
ft²
a
MW
shares
Corporate Office Properties, L.P | COPT | Preferred units          
Investments in real estate          
Limited partners' capital account, units outstanding (in shares) | shares         0
Common Units | Corporate Office Properties, L.P | COPT          
Investments in real estate          
Percentage ownership in operating partnership 98.30%        
Operating properties          
Investments in real estate          
Number of real estate properties 186        
Area of real estate property (in sqft or acres) | ft²   21.7      
Operating properties | Office Properties          
Investments in real estate          
Number of real estate properties 160        
Area of real estate property (in sqft or acres) | ft²   17.0      
Operating properties | Single-tenant data centers          
Investments in real estate          
Number of real estate properties 26        
Area of real estate property (in sqft or acres) | ft²   4.7      
Wholesale Data Center          
Investments in real estate          
Capacity (in megawatts) | MW       19.25  
Properties under development          
Investments in real estate          
Number of real estate properties 11        
Area of real estate property (in sqft or acres) | ft²   1.7      
Properties under development | Office Properties          
Investments in real estate          
Number of real estate properties 8        
Properties under development | Single-tenant data centers          
Investments in real estate          
Number of real estate properties 3        
Properties Under Development, Partially-Operational          
Investments in real estate          
Number of real estate properties 1        
Land controlled for future development          
Investments in real estate          
Area of real estate property (in sqft or acres)   8.9 720    
Other land          
Investments in real estate          
Area of real estate property (in sqft or acres) | a     43    
Unconsolidated Real Estate Joint Ventures          
Investments in real estate          
Number of real estate properties 19        
Unconsolidated Real Estate Joint Ventures | Operating properties | Single-tenant data centers          
Investments in real estate          
Number of real estate properties 19