Quarterly report pursuant to Section 13 or 15(d)

Properties, Net (Details 4)

v3.7.0.1
Properties, Net (Details 4)
ft² in Thousands
 6 Months Ended
Jun. 09, 2017
USD ($)
ft²
Feb. 15, 2017
USD ($)
ft²
Jun. 30, 2017
USD ($)
ft²
Property
Jul. 28, 2017
USD ($)
ft²
Property
Construction, Redevelopment and Dispositions        
Sale price of land | $     $ 14,300,000  
Gain on sale of land | $     $ 4,200,000  
Office properties under, or contractually committed for, construction or approved for redevelopment        
Construction, Redevelopment and Dispositions        
Square footage of real estate properties (in square feet) | ft²     1,400  
Number of real estate properties     10  
Newly constructed properties placed in service        
Construction, Redevelopment and Dispositions        
Number of real estate properties     3  
Square feet of properties placed in service | ft²     295  
Newly redeveloped properties placed in service        
Construction, Redevelopment and Dispositions        
Number of real estate properties     3  
Square feet of properties placed in service | ft²     88  
Partially operational properties        
Construction, Redevelopment and Dispositions        
Number of real estate properties     2  
Partially operational properties | Office properties under, or contractually committed for, construction or approved for redevelopment        
Construction, Redevelopment and Dispositions        
Number of real estate properties     3  
Properties under construction or contractually committed for construction        
Construction, Redevelopment and Dispositions        
Square footage of real estate properties (in square feet) | ft²     1,300  
Number of real estate properties     8  
Properties completed Held-for-future lease | Office properties under, or contractually committed for, construction or approved for redevelopment        
Construction, Redevelopment and Dispositions        
Number of real estate properties     2  
Properties under or approved for redevelopment        
Construction, Redevelopment and Dispositions        
Square footage of real estate properties (in square feet) | ft²     61  
Number of real estate properties     2  
Operating Properties | Regional Office | White Marsh, Maryland | Subsequent Event        
Construction, Redevelopment and Dispositions        
Square footage of real estate properties (in square feet) | ft²       412
Transaction value | $       $ 47,500,000
Number of real estate properties       8
Operating Properties | Northern Virginia Defense/IT | Defense/Information Technology Locations | 3120 Fairview Park Drive        
Construction, Redevelopment and Dispositions        
Square footage of real estate properties (in square feet) | ft²   190    
Transaction value | $   $ 39,000,000    
Gain recognized | $   $ 0    
Operating Properties | Fort Meade/BW Corridor | Defense/Information Technology Locations | 1334 Ashton Road        
Construction, Redevelopment and Dispositions        
Square footage of real estate properties (in square feet) | ft² 37      
Transaction value | $ $ 2,300,000      
Gain recognized | $ $ 0