Share Capital (Schedule Of Common Stock Issued And Outstanding) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share Capital [Abstract]
Common Shares Outstanding, Beginning of Year, Shares	973,000,000	849,800,000	741,200,000
Stock Issued During Period, Shares, New Issues		123,100,000	98,400,000
Common Shares Issued under Dividend Reinvestment Plan, Shares	58,480	121,249	10,246,221
Common Shares Outstanding, End of Period, Shares	973,100,000	973,000,000	849,800,000
Common Shares Outstanding, Beginning of Year	$ 4,756.0	$ 3,621.0	$ 2,450.0
Stock Issued During Period, Value, New Issues		1,134.0	1,098.0
Common Shares Issued under Dividend Reinvestment Plan	0.6	0.9	73.0
Common Shares Outstanding, End of Period	$ 4,757.0	$ 4,756.0	$ 3,621.0