Earnings Per Share and Equity (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Earnings Per Share And Equity Additional Narrative Information [Abstract]
Stock options not included in the calculation of diluted common shares outstanding	17	17	18	13
Treasury Stock, Shares held	35		35		35
Treasury stock, at cost	$ 2,327		$ 2,327		$ 2,327
Preferred Stock [Line Items]
Preferred stock redemption premium			(6)
Earnings Per Share Diluted
Net income on common stock	490	286	486	486
Average common shares outstanding - basic	856	853	856	779
Assumed exercise of stock options, performance share awards and restricted stock	4	3	3	2
Average common shares outstanding - diluted	860	856	859	781
Preferred securities	0		0		87
Preferred Stock [Member] | Cumulative Preferred Stock [Member]
Preferred Stock [Line Items]
PECO Cumulative Preferred Securities Redeemable	87
Retained Earnings | Cumulative Preferred Stock [Member]
Preferred Stock [Line Items]
Preferred stock redemption premium	$ 6