Common Shareholders' Equity (Issuance of Common Stock and Forward Sale Agreement) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended
	Nov. 30, 2013	Dec. 31, 2014
Class of Stock [Line Items]
Stock sold during the period	4.5
Share Price (in dollars per share)	$ 88.03
Forward Counterparty [Member]
Class of Stock [Line Items]
Stock sold during the period	6.6
Shares delivered		6.6
Proceeds from Equity		$ 552