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