Organization and Offering (Narratives) (Details) (USD $)	0 Months Ended	12 Months Ended			21 Months Ended
	Apr. 07, 2011	Dec. 31, 2012 property tenant sqft	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 property tenant sqft	Jan. 31, 2013
Business and Organization
Number of Real Estate Properties		335			335
Number Of Tenants		80			80
Square footage of real estate property		32,000,000			32,000,000
Number of self storage properties		58			58
Square footage of self storage properties		4,000,000			4,000,000
Operating Partnership Interest		0.015%			0.015%
Percentage Of General And Limited Partnership Interest		99.985%			99.985%
Public Offerings [Abstract]
Proceeds from Issuance Initial Public Offering	$ 1,500,000,000
Maximum Proceeds from Issuance Follow On Offering					1,000,000,000
Maximum Proceeds From Issuance Drip Follow on offering					475,000,000
Allocation of shares from Drip to offering					35,000,000
Proceeds from Issuance Follow On Offering, Shares					289,000,000
Proceeds from Issuance Follow On Offering, Value		903,229,000	571,655,000	557,895,000	2,900,000,000
Shares Issued From Drip in Follow On Public Offering					17,691,063
Proceeds From Issuance Drip Follow On Public Offering					168,100,000
Stock Repurchased During Period Shares					3,645,644
Stock Repurchased During Period Value					$ 34,300,000
Total Shares Authorized						950,000,000
Common Stock Shares Authorized		400,000,000			400,000,000	900,000,000
Common Stock Par Or Stated Value Per Share		$ (0.001)			$ (0.001)	$ 0.001
Preferred Stock Shares Authorized		50,000,000			50,000,000	50,000,000
Preferred Stock Par Or Stated Value Per Share		$ 0.001			$ 0.001	$ 0.001
Total Shares Authorized For Dividend Reinvestment Plan						20,000,000