Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Real Estate and Depreciation (Details)

v2.4.0.6
Summary of Significant Accounting Policies - Real Estate and Depreciation (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended 3 Months Ended 12 Months Ended 3 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2012
Minimum [Member]
Dec. 31, 2012
Minimum [Member]
Building [Member]
Dec. 31, 2012
Minimum [Member]
Building and Building Improvements [Member]
Dec. 31, 2012
Maximum [Member]
Dec. 31, 2012
Maximum [Member]
Building [Member]
Dec. 31, 2012
Maximum [Member]
Building and Building Improvements [Member]
Dec. 31, 2012
4661 Kenmore Avenue [Member]
Dec. 31, 2011
Dulles Station, Phase I [Member]
Dec. 31, 2011
Dulles Station II [Member]
Property, Plant and Equipment [Line Items]                        
Useful Life       3 years 28 years 3 years 50 years 50 years 30 years      
Real estate depreciation $ 76,824 $ 69,753 $ 63,372                  
Total interest expense from continuing operations 66,385 66,952 67,823                  
Capitalized interest 1,688 738 858                  
Interest expense, net of capitalized interest 64,697 66,214 66,965                  
Impairment of real estate $ 2,097 $ 14,526 $ 0             $ 2,100 $ 600 $ 14,500