Annual report pursuant to Section 13 and 15(d)

Properties, Net (Narrative) (Details)

v3.19.3.a.u2
Properties, Net (Narrative) (Details)
ft² in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2018
USD ($)
ft²
property
Dec. 31, 2019
USD ($)
ft²
property
Dec. 31, 2018
USD ($)
ft²
property
Dec. 31, 2017
USD ($)
ft²
property
Dec. 05, 2019
property
Jun. 20, 2019
property
Oct. 27, 2017
USD ($)
ft²
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]              
Impairment charges   $ 329,000 $ 2,367,000 $ 15,116,000      
Newly-developed properties placed in service              
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]              
Number of real estate properties | property 6 9 6 8      
Area of real estate property (in sqft or acres) | ft² 666 1,100 666 1,100      
Redeveloped Property Placed in Service, Partially-Operational              
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]              
Number of real estate properties | property   1          
Area of real estate property (in sqft or acres) | ft²   85          
Properties under development or Contractually Commited for Construction              
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]              
Number of real estate properties | property   13          
Area of real estate property (in sqft or acres) | ft²   2,300          
Properties Under Or Approved For Redevelopment, Partially-Operational              
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]              
Number of real estate properties | property   1          
Area of real estate property (in sqft or acres) | ft²   106          
Newly-developed properties placed in service, partially operational              
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]              
Number of real estate properties | property 2   2        
Newly redeveloped properties placed In service              
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]              
Number of real estate properties | property 1   1 3      
Area of real estate property (in sqft or acres) | ft² 22   22 94      
Disposed of by sale              
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]              
Number of real estate properties | property       12      
Transaction Value       $ 125,829,000      
Gain (loss) on disposal       $ 5,636,000      
Area of real estate property (in sqft or acres) | ft²       799      
Proceeds from sale of land held-for-investment       $ 14,300,000      
Gains on sale of other land       $ 4,200,000      
Fort Meade/BW Corridor sub-segment              
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]              
Impairment charges $ 2,400,000            
BREIT COPT DC JV LLC | Variable Interest Entity, Not Primary Beneficiary              
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]              
Ownership percentage   10.00%          
Data Center Shells in Northern Virginia | Disposed of by sale              
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]              
Ownership percentage sold   90.00%          
Number of real estate properties | property   9     2 7  
Transaction Value   $ 345,100,000          
Proceeds from divestiture of businesses   310,600,000          
Gain (loss) on disposal   $ 105,200,000          
Data Center Shells in Chester, Virginia | Disposed of by sale              
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]              
Transaction Value             $ 44,000,000.0
Gain (loss) on disposal $ 1,500,000            
Area of real estate property (in sqft or acres) | ft²             193
Maximum exposure             $ 20,000,000