Quarterly report pursuant to Section 13 or 15(d)

Real Estate Real Estate Acquisition (Details)

v2.4.0.6
Real Estate Real Estate Acquisition (Details) (USD $)
6 Months Ended
Jun. 30, 2012
Dec. 31, 2011
Business Acquisition [Line Items]    
Credits Received At Settlement $ 100,000  
Real estate investment property, at cost 2,478,281,000 2,406,783,000
Property Acquired Member | Fairgate at Ballston [Member]
   
Business Acquisition [Line Items]    
Rentable square feet 147,000  
Real estate investment property, at cost $ 52,250,000