Annual report pursuant to Section 13 and 15(d)

Real Estate Joint Ventures (Details)

v3.6.0.2
Real Estate Joint Ventures (Details)
$ in Thousands
1 Months Ended 12 Months Ended
Jul. 21, 2016
USD ($)
Aug. 07, 2014
USD ($)
Jan. 31, 2016
USD ($)
Dec. 31, 2016
USD ($)
ft²
buillding
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Investments in consolidated real estate joint ventures            
Increase in property and redeemable noncontrolling interests in connection with property contribution by a redeemable noncontrolling interest in a joint venture       $ 22,600 $ 0 $ 0
Investing receivables       52,279 47,875  
Non-real estate equity method investments       2,355 1,636  
Notes receivable from City of Huntsville [Member]            
Investments in consolidated real estate joint ventures            
Amount of advanced       37,200    
Investing receivables       $ 49,258 $ 44,875  
Single-tenant data centers [Member] | Operating office properties [Member]            
Investments in consolidated real estate joint ventures            
Increase in property and redeemable noncontrolling interests in connection with property contribution by a redeemable noncontrolling interest in a joint venture $ 147,600          
Ownership percentage sold (percent) 50.00%          
Ownership percentage 50.00%          
Data Center Shells [Member] | Operating properties, net [Member] | Single-tenant data centers [Member] | Operating office properties [Member]            
Investments in consolidated real estate joint ventures            
Number of properties contributed | buillding       6    
LW Redstone Company, LLC [Member]            
Investments in consolidated real estate joint ventures            
Partner's capital account upon formation       $ 9,000    
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       4,400,000.0    
Construction commencement completed (in sqft) | ft²       594,000    
LW Redstone Company, LLC [Member] | Maximum [Member]            
Investments in consolidated real estate joint ventures            
Infrastructure costs anticipated to be funded by entity for reimbursement by the City of Huntsville (in dollars)       $ 76,000    
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 [Member] | Minimum [Member]            
Investments in consolidated 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 [Member]            
Investments in consolidated real estate joint ventures            
Percentage of residual amounts distributed to each member       50.00%    
Consolidated real estate joint ventures [Member]            
Investments in consolidated real estate joint ventures            
Total Assets       $ 266,570    
Encumbered Assets       125,778    
Total Liabilities       104,166    
GI-COPT [Member]            
Investments in consolidated real estate joint ventures            
Non-real estate equity method investments       25,500    
Difference between cost basis and share of underlying equity       $ 18,100    
LW Redstone Company, LLC [Member] | Primary Beneficiary [Member]            
Investments in consolidated real estate joint ventures            
Ownership (as a percent)       85.00%    
Total Assets       $ 156,745    
Encumbered Assets       79,215    
Total Liabilities       $ 51,207    
M Square Associates, LLC [Member] | Primary Beneficiary [Member]            
Investments in consolidated real estate joint ventures            
Ownership (as a percent)       50.00%    
Total Assets       $ 68,900    
Encumbered Assets       46,563    
Total Liabilities       $ 45,966    
Stevens Investors, LLC [Member] | Primary Beneficiary [Member]            
Investments in consolidated real estate joint ventures            
Ownership (as a percent)       95.00%    
Total Assets       $ 40,925    
Encumbered Assets       0    
Total Liabilities       6,993    
Increase in property and redeemable noncontrolling interests in connection with property contribution by a redeemable noncontrolling interest in a joint venture     $ 22,600      
Cash distribution     $ 13,400      
Stevens Investors, LLC [Member] | Other Liabilities [Member] | Primary Beneficiary [Member]            
Investments in consolidated real estate joint ventures            
Due to affiliate       $ 6,700    
COPT-FD Indian Head LLC [Member] | Primary Beneficiary [Member]            
Investments in consolidated real estate joint ventures            
Proceeds from real estate and real estate joint ventures   $ 6,400