Annual report pursuant to Section 13 and 15(d)

Real Estate Joint Ventures (Narrative) (Details)

v3.20.4
Real Estate Joint Ventures (Narrative) (Details)
$ in Thousands, ft² in Millions
12 Months Ended
Dec. 22, 2020
USD ($)
property
Dec. 31, 2020
USD ($)
ft²
Dec. 31, 2019
USD ($)
property
Dec. 31, 2018
USD ($)
Dec. 21, 2020
Oct. 30, 2020
property
Investments in real estate joint ventures            
Ownership percentage sold     90.00%     90.00%
Number of properties sold | property     9     2
Gain on sale of investment in unconsolidated real estate joint venture   $ 29,416 $ 0 $ 0    
GI-COPT DC Partnership LLC            
Investments in real estate joint ventures            
Ownership interest sold of the original 50% owned 80.00%          
Ownership percentage     50.00%   50.00%  
Proceeds from sale of investment in unconsolidated real estate joint venture $ 60,000          
Gain on sale of investment in unconsolidated real estate joint venture $ 29,400          
BREIT COPT DC JV LLC            
Investments in real estate joint ventures            
Ownership percentage   10.00% 10.00%      
B RE COPT DC JV II LLC            
Investments in real estate joint ventures            
Ownership percentage 10.00% 10.00%       10.00%
LW Redstone Company, LLC            
Investments in real estate joint ventures            
Partner's capital account upon formation   $ 9,000        
Percentage of cumulative preferred returns of cash flows on partners' invested capital   13.50%        
Percentage of cumulative preferred returns of cash flows on our invested capital   13.50%        
Percentage of residual distributable cash flows in excess of unpaid cumulative preferred returns and return of invested capital entitled to the company   85.00%        
Percentage of residual distributable cash flows in excess of unpaid cumulative preferred returns and return of invested capital entitled to the entity's partners   15.00%        
Number of years following construction commencement threshold achievement before partner's interest can be purchased at fair value   5 years        
Construction commencement threshold (in square feet) | ft²   4.4        
Construction commencement completed (in sqft) | ft²   1.6        
LW Redstone Company, LLC | Maximum            
Investments in real estate joint ventures            
Infrastructure costs anticipated to be funded by entity for reimbursement by the City of Huntsville (in dollars)   $ 76,000        
LW Redstone Company, LLC | Notes receivable from the City of Huntsville            
Investments in real estate joint ventures            
Infrastructure costs funded to date for reimbursement by the City of Huntsville   $ 61,000        
Stevens Investors, LLC | Maximum            
Investments in real estate joint ventures            
Percentage of residual distributable cash flows in excess of unpaid cumulative preferred returns and return of invested capital entitled to the company   85.00%        
Stevens Investors, LLC | Minimum            
Investments in real estate joint ventures            
Percentage of residual distributable cash flows in excess of unpaid cumulative preferred returns and return of invested capital entitled to the company   60.00%        
M Square Associates, LLC            
Investments in real estate joint ventures            
Percentage of residual amounts distributed to each member   50.00%        
GI-COPT DC Partnership LLC | B RE COPT DC JV II LLC            
Investments in real estate joint ventures            
Number of properties sold | property 6