Common Stock (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Common Stock [Line Items]
Average shares, basic	707	706	707	705
Average shares, diluted	707	706	707	706
EPS, basic (usd per share)	$ 0.86	$ 0.48	$ 0.73	$ 1.37
EPS, diluted (usd per share)	$ 0.86	$ 0.48	$ 0.73	$ 1.37
Number of stock options and performance and unvested stock awards excluded from the dilutive securities calculation			2	2
Dividends declared per share (usd per share)	$ 0.78	$ 1.545	$ 1.56	$ 2.31
Income [Member]
Common Stock [Line Items]
Income from continuing operations attributable to Duke Energy common shareholders, as adjusted for participating securities — basic and diluted	$ 611	$ 340	$ 516	$ 969
Average Shares [Member]
Common Stock [Line Items]
Stock options, performance and restricted shares				1
Average shares, basic and diluted	707	706	707
Average shares, basic				705
Average shares, diluted				706
EPS [Member]
Common Stock [Line Items]
EPS, basic and diluted (usd per share)	$ 0.86	$ 0.48	$ 0.73
EPS, basic (usd per share)				$ 1.37
EPS, diluted (usd per share)				$ 1.37