Guarantees (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended						12 Months Ended			12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Progress Energy Florida [Member]	Dec. 31, 2011 Progress Energy Florida [Member]	Dec. 31, 2012 Cresent [Member]	Dec. 31, 2009 Cresent [Member]	Dec. 31, 2012 DukeSolultions [Member]	Dec. 31, 2012 Performance Guarantee [Member]	Dec. 31, 2012 Indemnification Agreement [Member] Spectra Capital [Member]	Dec. 31, 2012 Indemnification Agreement [Member] Progress Energy [Member]	Dec. 31, 2011 Indemnification Agreement [Member] Progress Energy [Member]	Dec. 31, 2012 Indemnification Agreement [Member] Progress Energy Florida [Member]	Dec. 31, 2012 Payment Guarantee [Member]	Dec. 31, 2012 Payment Guarantee [Member] Progress Energy [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted							$ 2.5	$ 243.0	$ 141.0	$ 217.0		$ 42.0	$ 26.0
Guarantee Obligations unlimited exposure	Duke Energy is unable to estimate the total potential amount of future payments under these indemnification agreements due to several factors, such as the unlimited exposure under certain guarantees.									Certain indemnifications related to discontinued operations have no limitations as to time or maximum potential future payments.
Guarantor Obligations Amounts Issued To Related Party								44						300
Guarantee Obligations Amount That Will Expire								93
Guarantees, performance risk percentage agreed by buyer							100.00%
Guarantees, other risk up to an aggregate maximum amount agreed by buyer							50.00%
Charge recorded						26
Guarantor Obligations, Current Carrying Value	$ 41	$ 19	$ 17	$ 37	$ 18	$ 70				$ 25	$ 63