Quarterly report [Sections 13 or 15(d)]

Real Estate Joint Ventures - Investments in Unconsolidated Real Estate Joint Ventures (Details)

v3.25.3
Real Estate Joint Ventures - Investments in Unconsolidated Real Estate Joint Ventures (Details)
$ in Thousands
Sep. 30, 2025
USD ($)
property
Dec. 31, 2024
USD ($)
Unconsolidated Real Estate Joint Ventures    
Schedule of Equity Method Investments [Line Items]    
Number of Properties | property 24  
Carrying Value of Investment $ 13,751 $ 35,951
Unconsolidated Real Estate Joint Ventures | Investment in unconsolidated real estate joint ventures    
Schedule of Equity Method Investments [Line Items]    
Carrying Value of Investment 36,300 39,400
Unconsolidated Real Estate Joint Ventures | Other liabilities    
Schedule of Equity Method Investments [Line Items]    
Carrying Value of Investment $ (22,600) (3,400)
Redshift JV LLC    
Schedule of Equity Method Investments [Line Items]    
Nominal Ownership % 10.00%  
Number of Properties | property 3  
Carrying Value of Investment $ 20,804 20,921
BREIT COPT DC JV LLC    
Schedule of Equity Method Investments [Line Items]    
Nominal Ownership % 10.00%  
Number of Properties | property 9  
Carrying Value of Investment $ 8,830 9,584
Quark JV LLC    
Schedule of Equity Method Investments [Line Items]    
Nominal Ownership % 10.00%  
Number of Properties | property 2  
Carrying Value of Investment $ 6,667 6,706
B RE COPT DC JV III LLC    
Schedule of Equity Method Investments [Line Items]    
Nominal Ownership % 10.00%  
Number of Properties | property 2  
Carrying Value of Investment $ (493) 2,149
B RE COPT DC JV II LLC    
Schedule of Equity Method Investments [Line Items]    
Nominal Ownership % 10.00%  
Number of Properties | property 8  
Carrying Value of Investment $ (22,057) (3,409)
Difference between the joint venture's lower cost basis and the entity's share of underlying equity in the net assets $ 6,500 $ 6,700