Organization (Details)
Mar. 31, 2015
Property
Debt in default of payment terms | Northern Virginia | Wholly owned subsidiary  
Investments in real estate  
Number of real estate properties 2
Operating office properties  
Investments in real estate  
Number of real estate properties 178
Square footage of real estate properties (in square feet) 17,700,000
Office properties under, or contractually committed for, construction or approved for redevelopment  
Investments in real estate  
Number of real estate properties 12
Square footage of real estate properties (in square feet) 1,400,000
Partially operational properties  
Investments in real estate  
Number of real estate properties 1
Land controlled for future development  
Investments in real estate  
Square footage of real estate properties (in square feet) 1,402
Developable square feet 17,600,000
Partially operational, wholesale data center  
Investments in real estate  
The expected stabilization critical load after completion of development (in megawatts) 19.25