Commitments and Contingencies (Schedule of Environmental Loss Contingencies)(Details) (USD $) In Millions, unless otherwise specified	3 Months Ended							3 Months Ended									3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Minimum [Member]	Mar. 31, 2013 Maximum [Member]	Mar. 31, 2012 Duke Energy Carolinas [Member]	Mar. 31, 2013 Duke Energy Carolinas [Member]	Dec. 31, 2012 Duke Energy Carolinas [Member]	Mar. 31, 2013 Duke Energy Carolinas [Member] Minimum [Member]	Mar. 31, 2013 Duke Energy Carolinas [Member] Maximum [Member]	Mar. 31, 2013 Duke Energy Ohio [Member]	Mar. 31, 2012 Duke Energy Ohio [Member]	Mar. 31, 2013 Duke Energy Ohio [Member] Minimum [Member]	Mar. 31, 2013 Duke Energy Ohio [Member] Maximum [Member]	Mar. 31, 2013 Duke Energy Indiana [Member]	Mar. 31, 2012 Duke Energy Indiana [Member]	Dec. 31, 2011 Duke Energy Indiana [Member]	Mar. 31, 2013 Duke Energy Indiana [Member] Minimum [Member]	Mar. 31, 2013 Duke Energy Indiana [Member] Maximum [Member]	Mar. 31, 2013 Progress Energy [Member]	Mar. 31, 2012 Progress Energy [Member]	Mar. 31, 2013 Progress Energy [Member] Minimum [Member]	Mar. 31, 2013 Progress Energy [Member] Maximum [Member]	Mar. 31, 2013 Duke Energy Progress [Member]	Mar. 31, 2012 Duke Energy Progress [Member]	Mar. 31, 2013 Duke Energy Progress [Member] Minimum [Member]	Mar. 31, 2013 Duke Energy Progress [Member] Maximum [Member]	Mar. 31, 2013 Duke Energy Florida [Member]	Mar. 31, 2012 Duke Energy Florida [Member]	Mar. 31, 2013 Duke Energy Florida [Member] Minimum [Member]	Mar. 31, 2013 Duke Energy Florida [Member] Maximum [Member]
Disclosure Environmental Matters Details [Line Items]
Beginning balance	$ 75	$ 61			$ 12	$ 12	$ 12			$ 15	$ 28			$ 8	$ 9	$ 9			$ 33	$ 23			$ 14	$ 11			$ 19	$ 12
Amounts accrued for environmental loss contingencies	2	4			1						2								1	5				(1)			1	6
Expenditures for environmental loss contingencies	(6)	(7)								(2)	(5)			(1)					(2)	(4)			(1)	(1)			(1)	(3)
Ending balance	71	58			13	12	12			13	25			7	9	9			32	24			13	9			19	15
Estimated cost of complying with EPA Mercury and Air Toxics Standards			$ 650	$ 800				$ 65	$ 85			$ 40	$ 85				$ 540	$ 600			$ 7	$ 30			$ 5	$ 10			$ 2	$ 20