Common Equity (Common Share Activity) (Details)	9 Months Ended
	Sep. 30, 2017 shares
Common Stock Oustanding [Roll Forward]
Shares outstanding, January 1, 2017 (in shares)	227,673,654
Shareowner Direct Plan issuances (in shares)	496,437
Equity-based compensation plans (in shares)	5,185
Other (in shares)	(45,847)
Shares outstanding, September 30, 2017 (in shares)	231,204,360
At-The-Market Offering Program [Member]
Common Stock Oustanding [Roll Forward]
At-the-market offering program (in shares)	3,074,931