Common Equity (Common Share Activity) (Details) - shares	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Common Stock Oustanding [Roll Forward]
Shares outstanding, January 1 (in shares)	226,918,432	[1]	221,871,360		221,887,338
Common stock issued during the period, Shareowner Direct Plan (in shares)	732,814		606,010		0
Equity-based compensation plans (in shares)	22,408		112,756		71,094
Other (in shares)	0		(44,928)		(87,072)
Shares outstanding, December 31 (in shares)	227,673,654	[1]	226,918,432	[1]	221,871,360
At The Market Offering Program [Member]
Common Stock Oustanding [Roll Forward]
Common stock issued during the period, At-the-market offering program (in shares)	0		4,373,234		0

[1] Amounts reflect the effects of a two-for-one common stock split distributed in May 2016.