Income Taxes (Schedule Of Unrecognized Tax Benefits) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011
Income Taxes [Abstract]
Amount that if recognized, would affect the effective tax rate or regulatory liability	$ 121	[1],[2]
Amount that if recognized, would be recorded as a component of discontinued operations	$ 11	[1]

[1] The Duke Registrants do not anticipate a material increase or decrease in unrecognized tax benefits in the next 12 months.

[2] Duke Energy and Duke Energy Carolinas are unable to estimate the specific amounts that would affect the effective tax rate or regulatory liability.