Annual report pursuant to Section 13 and 15(d)

Organization (Details)

v3.8.0.1
Organization (Details) - Dec. 31, 2017
ft² in Millions
a
ft²
MW
Property
Operating properties [Member]        
Investments in real estate        
Number of real estate properties       159
Area of real estate property (in sqft or acres) | ft²   17.3    
Operating properties [Member] | Single-tenant data centers [Member]        
Investments in real estate        
Number of real estate properties       15
Operating properties [Member] | Office Properties [Member]        
Investments in real estate        
Number of real estate properties       144
Office properties under, or contractually committed for, construction or approved for redevelopment [Member]        
Investments in real estate        
Number of real estate properties       10
Area of real estate property (in sqft or acres) | ft²   1.1    
Office properties under, or contractually committed for, construction or approved for redevelopment [Member] | Single-tenant data centers [Member]        
Investments in real estate        
Number of real estate properties       3
Office properties under, or contractually committed for, construction or approved for redevelopment [Member] | Office Properties [Member]        
Investments in real estate        
Number of real estate properties       7
Office properties under, or contractually committed for, construction or approved for redevelopment [Member] | Partially operational properties [Member]        
Investments in real estate        
Number of real estate properties       2
Office properties under, or contractually committed for, construction or approved for redevelopment [Member] | Properties completed Held-for-future lease [Member]        
Investments in real estate        
Number of real estate properties       2
Land controlled for future development [Member]        
Investments in real estate        
Area of real estate property (in sqft or acres) 1,000 13.0    
Other land [Member]        
Investments in real estate        
Area of real estate property (in sqft or acres) | a 150      
Operating wholesale data centers [Member]        
Investments in real estate        
Critical load (in megawatts) | MW     19.25  
GI-COPT [Member] | Operating properties [Member] | Single-tenant data centers [Member]        
Investments in real estate        
Number of real estate properties       6