Quarterly report pursuant to Section 13 or 15(d)

Fair Value Disclosures - Financial Assets and Liabilities Not Measured at Fair Value (Details)

v2.4.0.8
Fair Value Disclosures - Financial Assets and Liabilities Not Measured at Fair Value (Details) (USD $)
In Thousands, unless otherwise specified
9 Months Ended
Sep. 30, 2013
Sep. 30, 2013
Carrying Value
Dec. 31, 2012
Carrying Value
Sep. 30, 2013
Carrying Value
2445 M Street Note Receivable [Member]
Dec. 31, 2012
Carrying Value
2445 M Street Note Receivable [Member]
Sep. 30, 2013
Fair Value
Dec. 31, 2012
Fair Value
Sep. 30, 2013
Fair Value
2445 M Street Note Receivable [Member]
Dec. 31, 2012
Fair Value
2445 M Street Note Receivable [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Commercial paper, maturity 90                
Cash and cash equivalents, Fair Value   $ 7,923 $ 19,324     $ 7,923 $ 19,324    
Restricted Cash, Fair Value   7,674 14,582     7,674 14,582    
2445 M Street note receivable, Fair Value       6,166 6,617     6,990 6,654
Mortgage notes payable, Fair Value   314,305 342,970     337,266 374,591    
Lines of credit payable, Fair Value   85,000 0     85,000 0    
Notes payable, Fair Value   $ 846,576 $ 906,190     $ 873,702 $ 968,040