Organization (Details Textual) (USD $)			0 Months Ended
	Dec. 31, 2012 Property	Dec. 31, 2011 Property	Mar. 31, 2009 Common Stock [Member] Distribution Reinvestment Plan [Member]	Aug. 31, 2005 Common Stock [Member] IPO [Member]	Aug. 31, 2005 Common Stock [Member] IPO [Member] Distribution Reinvestment Plan [Member]	Aug. 01, 2007 Common Stock [Member] Second Public Offering [Member]	Aug. 01, 2007 Common Stock [Member] Second Public Offering [Member] Distribution Reinvestment Plan [Member]
Class of Stock [Line Items]
Number of shares issued			50,000,000	500,000,000	40,000,000	500,000,000	40,000,000
Share price				$ 10.00	$ 9.50	$ 10.00	$ 9.50
Number of company owned commercial real estate properties	794	964