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, 2014
Sep. 30, 2014
Reported Value Measurement [Member]
Dec. 31, 2013
Reported Value Measurement [Member]
Sep. 30, 2014
Reported Value Measurement [Member]
2445 M Street Note Receivable [Member]
Dec. 31, 2013
Reported Value Measurement [Member]
2445 M Street Note Receivable [Member]
Sep. 30, 2014
Fair Value
Dec. 31, 2013
Fair Value
Sep. 30, 2014
Fair Value
2445 M Street Note Receivable [Member]
Dec. 31, 2013
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   $ 8,571 $ 130,343     $ 8,571 $ 130,343    
Restricted Cash, Fair Value   9,496 9,189     9,496 9,189    
2445 M Street note receivable, Fair Value       5,556 6,070     6,755 6,803
Mortgage notes payable, Fair Value   413,330 294,671     429,957 313,476    
Lines of Credit, Fair Value Disclosure   5,000 0     5,000 0    
Notes payable, Fair Value   $ 747,082 $ 846,703     $ 782,450 $ 856,171