Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Line Items]
Average shares, basic	706	699	706	531
Average shares, diluted	706	699	706	531
EPS, basic	$ 1.40	$ 0.84	$ 2.78	$ 2.50
EPS, diluted	$ 1.40	$ 0.84	$ 2.78	$ 2.50
Number of stock options and performance and unvested stock awards excluded from the dilutive securities calculation			2	1
Income [Member]
Earnings Per Share [Line Items]
Income from continuing operations attributable to Duke Energy common stockholders, as adjusted for participating securities - basic and diluted	$ 989	$ 589	$ 1,959	$ 1,326
Average Shares [Member]
Earnings Per Share [Line Items]
Average shares, basic and diluted	706	699	706	531
EPS [Member]
Earnings Per Share [Line Items]
EPS, basic and diluted	$ 1.40	$ 0.84	$ 2.78	$ 2.50