Stock-Based Compensation (Schedule Of Shares Awarded) (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards granted	443		636		349
Fair Value	$ 28	[1]	$ 34	[1]	$ 17	[1]
Performance Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards granted	352		432		912
Fair Value	$ 19	[1]	$ 20	[1]	$ 38	[1]

[1] Based on the market price of Duke Energy's common stock at the grant date.