Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010
Earnings Per Share [Line Items]
Income from continuing operations attributable to Duke Energy common stockholders, as adjusted for participating securities - basic									$ 1,780	[1]
Average shares, basic									574		444	439
Average shares, diluted									575		444	440
EPS, basic and diluted											$ 3.83
EPS, basic	$ 0.57	$ 0.84	$ 0.99	$ 0.66	$ 0.65	$ 1.06	$ 0.98	$ 1.15	$ 3.01		$ 3.83	$ 2.99
EPS, diluted	$ 0.57	$ 0.84	$ 0.99	$ 0.66	$ 0.65	$ 1.06	$ 0.98	$ 1.15	$ 3.01		$ 3.83	$ 2.99
Proceeds from Issuances of Common Stock - Narrative												288
Value of stock options, performance and unvested stock awards not included in the effect of dilutive securities									1		3	5
Progress Energy [Member]
Earnings Per Share [Line Items]
EPS, basic			$ 0.23	$ 0.47	$ (0.25)	$ 0.98	$ 0.60	$ 0.63
EPS, diluted			$ 0.23	$ 0.47	$ (0.25)	$ 0.98	$ 0.60	$ 0.63
Value of stock options, performance and unvested stock awards not included in the effect of dilutive securities												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											1,702
Income from continuing operations attributable to Duke Energy common stockholders, as adjusted for participating securities - basic									1,727			1,315
Income from continuing operations attributable to Duke Energy common stockholders, as adjusted for participating securities - diluted									1,727			1,315
Income [Member] | Progress Energy [Member]
Earnings Per Share [Line Items]
Income from continuing operations attributable to Duke Energy common stockholders, as adjusted for participating securities - basic and diluted											$ 580	$ 860
Average Shares [Member]
Earnings Per Share [Line Items]
Stock options, performance and restricted stock									1
Average shares, basic and diluted											444
Average shares, basic									574			439
Average shares, diluted									575			440
Value of stock options, performance and unvested stock awards not included in the effect of dilutive securities												1
Average Shares [Member] | Progress Energy [Member]
Earnings Per Share [Line Items]
Average shares, basic and diluted											296	291
Eps [Member]
Earnings Per Share [Line Items]
EPS, basic									$ 3.01			$ 2.99
EPS, diluted									$ 3.01			$ 2.99
Eps [Member] | Progress Energy [Member]
Earnings Per Share [Line Items]
EPS, basic and diluted											$ 1.96	$ 2.96

[1] For the year ended December 31, 2012, consolidated net income of $1,782 million includes $2 million attributable to preferred shareholders of subsidiaries. Income attributable to preferred shareholders of subsidiaries is not a component of total equity and is excluded from the table above.