Quarterly report [Sections 13 or 15(d)]

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

v3.26.1
Real Estate Joint Ventures - Investments in Unconsolidated Real Estate Joint Ventures (Details)
$ in Thousands
Mar. 31, 2026
USD ($)
property
Dec. 31, 2025
USD ($)
Unconsolidated Real Estate Joint Ventures    
Schedule of Equity Method Investments [Line Items]    
Number of Properties | property 24  
Carrying Value of Investment $ 11,805 $ 13,525
Unconsolidated Real Estate Joint Ventures | Investment in unconsolidated real estate joint ventures    
Schedule of Equity Method Investments [Line Items]    
Carrying Value of Investment 35,800 36,400
Unconsolidated Real Estate Joint Ventures | Other liabilities    
Schedule of Equity Method Investments [Line Items]    
Carrying Value of Investment $ (24,000) (22,800)
Redshift JV LLC    
Schedule of Equity Method Investments [Line Items]    
Nominal Ownership % 10.00%  
Number of Properties | property 3  
Carrying Value of Investment $ 20,196 20,767
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 $ 8,970 8,941
Quark JV LLC    
Schedule of Equity Method Investments [Line Items]    
Nominal Ownership % 10.00%  
Number of Properties | property 2  
Carrying Value of Investment $ 6,652 6,660
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 $ (707) (600)
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 $ (23,306) (22,243)
Difference between the joint venture's lower cost basis and the entity's share of underlying equity in the net assets $ 6,400 $ 6,500