Organization (Public Offering) (Details)				3 Months Ended	56 Months Ended	104 Months Ended
	Apr. 24, 2014	Apr. 11, 2014	Aug. 05, 2009	Mar. 31, 2018 USD ($)	Apr. 11, 2014 public_offering	Mar. 31, 2018 USD ($)
Public Offerings
Public Offering [Line Items]
Number of public offerings | public_offering					2
Proceeds from sale of common stock						$ 3,100,000,000
First Offering
Public Offering [Line Items]
Commencement date, public offering			Aug. 05, 2009
Second Offering
Public Offering [Line Items]
Termination date, public offering		Apr. 11, 2014
Dividend Reinvestment Plan
Public Offering [Line Items]
Commencement date, public offering	Apr. 24, 2014
Maximum proceeds authorized for public offering				$ 500,000,000.0