Acquisitions and Sales of Other Assets (Pro Forma Financial Information) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Significant Acquisitions and Disposals [Line Items]
Revenues	$ 23,976	$ 23,445
Net Income Attributable to Duke Energy Corporation	$ 2,417	$ 2,397
Basic Earnings Per Share	$ 3.43	$ 3.41
Diluted Earnings Per Share	$ 3.43	$ 3.41