Organization, Formation, and Basis of Presentation - Real Estate Properties Acquired ,Developed and/or Disposed (Detail)
 1 Months Ended 24 Months Ended 1 Months Ended
Jul. 31, 2012
West Park
Dec. 31, 2012
Belvedere
Dec. 31, 2011
Business Development One
Dec. 31, 2011
Business Development One
Minimum
Dec. 31, 2011
Business Development One
Maximum
Dec. 31, 2011
Business Development Two
Dec. 31, 2011
Business Development Two
Minimum
Dec. 31, 2011
Business Development Two
Maximum
Feb. 28, 2011
Business Acquisition Three
Sep. 30, 2011
Business Acquisition Four
Sep. 30, 2011
Business Acquisition Five
Sep. 30, 2011
Business Acquisition Six
Dec. 31, 2012
Business Acquisition Seven
Dec. 31, 2012
Business Acquisition Eight
Real Estate Properties [Line Items]                            
Name of Property West Park Belvedere Clarendon Center North     Clarendon Center South                
Location Oklahoma City, Oklahoma Baltimore, Maryland Arlington, Virginia     Arlington, Virginia                
Type Shopping Center Shopping Center Mixed-Use     Mixed-Use     Shopping Center Shopping Center Shopping Center Shopping Center Shopping Center Shopping Center
Year of Acquisition                 Feb. 28, 2011 Sep. 30, 2011 Sep. 30, 2011 Sep. 30, 2011 Dec. 31, 2012 Dec. 31, 2012
Year of Development       2010 2011   2010 2011            
Year of Disposal Jul. 31, 2012 Dec. 31, 2012