Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Share [Line Items]
Average shares, basic	706	446	705	446
Average shares, diluted	706	446	706	446
EPS, basic	$ 0.48	$ 0.99	$ 1.37	$ 1.65
EPS, diluted	$ 0.48	$ 0.99	$ 1.37	$ 1.65
Number of stock options and performance and unvested stock awards excluded from the dilutive securities calculation			2	4
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	$ 340	$ 444	$ 969	$ 736
Average Shares [Member]
Earnings Per Share [Line Items]
Stock options, performance and restricted stock			1
Average shares, basic and diluted	706	446		446
Average shares, basic			705
Average shares, diluted			706
EPS [Member]
Earnings Per Share [Line Items]
EPS, basic and diluted	$ 0.48	$ 0.99	$ 1.37	$ 1.65

Net income loss available to common stockholders basic and diluted

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The amount of net income (loss) from continuing operations per each basic and diluted share of common stock or unit when the per share amount is the same for both basic and diluted shares.

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