Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Excise Taxes)(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Organization And Basis Of Presentation [Line Items]
Excise taxes	$ 396	$ 498	$ 602
Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	31	94	164
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	229	263	304
Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	16	56	115
Duke Energy Florida [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	213	207	189
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	102	103	105
Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	$ 34	$ 38	$ 29