Stock-Based Compensation (Schedule Of Shares Awarded) (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Phantom Awards [Member]
Stock awards granted	1,907		1,047		1,096
Fair Value	$ 34	[1]	$ 17	[1]	$ 16	[1]
Performance Awards [Member]
Stock awards granted	1,294		2,734		3,426
Fair Value	$ 20	[1]	$ 38	[1]	$ 44	[1]

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