Organization and Offering (Narratives) (Details) (USD $)	1 Months Ended	9 Months Ended	12 Months Ended
	Jan. 31, 2013	Sep. 30, 2013 property sqft tenant	Dec. 31, 2012
Business and Organization
Number of real estate properties		343
Number of tenants		88
Square footage of real estate properties		33,000,000
Real Estate Properties [Line Items]
Square footage of operating properties		6,000,000
Capital interest in operating partnership		99.985%
Public Offerings
Proceeds from issuance follow-on offering, shares	289,000,000
Proceeds from issuance follow-on offering, value	$ 2,900,000,000	$ 71,921,000	$ 903,229,000
Shares issued from DRIP in follow-on public offering		25,236,318
Proceeds from issuance DRIP follow-on public offering		239,700,000
Stock repurchased during period, shares		5,070,000
Stock repurchased during period, value		$ 47,700,000
Total shares authorized	950,000,000
Common stock shares authorized	900,000,000	900,000,000
Common stock, par or stated value per share	$ 0.001	$ 0.001
Preferred stock shares authorized	50,000,000	50,000,000
Preferred stock, par or stated value per share	$ 0.001	$ 0.001
Total shares authorized for dividend reinvestment plan	200,000,000
Self storage
Real Estate Properties [Line Items]
Number of operating properties		69
Hotel
Real Estate Properties [Line Items]
Number of operating properties		3
Shopping center
Real Estate Properties [Line Items]
Number of operating properties		1