Commitments and Contingencies (Schedule of Environmental Loss Contingencies)(Details) (USD $) In Millions, unless otherwise specified	12 Months Ended								12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Minimum [Member]	Dec. 31, 2012 Maximum [Member]	Dec. 31, 2012 Duke Energy Carolinas [Member]	Dec. 31, 2011 Duke Energy Carolinas [Member]	Dec. 31, 2009 Duke Energy Carolinas [Member]	Dec. 31, 2012 Duke Energy Carolinas [Member] Minimum [Member]	Dec. 31, 2012 Duke Energy Carolinas [Member] Maximum [Member]	Dec. 31, 2012 Duke Energy Ohio [Member]	Dec. 31, 2011 Duke Energy Ohio [Member]	Dec. 31, 2010 Duke Energy Ohio [Member]	Dec. 31, 2012 Duke Energy Ohio [Member] Minimum [Member]	Dec. 31, 2012 Duke Energy Ohio [Member] Maximum [Member]	Dec. 31, 2012 Duke Energy Indiana [Member]	Dec. 31, 2011 Duke Energy Indiana [Member]	Dec. 31, 2010 Duke Energy Indiana [Member]	Dec. 31, 2012 Duke Energy Indiana [Member] Minimum [Member]	Dec. 31, 2012 Duke Energy Indiana [Member] Maximum [Member]	Dec. 31, 2012 Progress Energy [Member]	Dec. 31, 2011 Progress Energy [Member]	Dec. 31, 2010 Progress Energy [Member]	Dec. 31, 2012 Progress Energy [Member] Minimum [Member]	Dec. 31, 2012 Progress Energy [Member] Maximum [Member]	Dec. 31, 2012 Progress Energy Carolinas [Member]	Dec. 31, 2011 Progress Energy Carolinas [Member]	Dec. 31, 2010 Progress Energy Carolinas [Member]	Dec. 31, 2012 Progress Energy Carolinas [Member] Minimum [Member]	Dec. 31, 2012 Progress Energy Carolinas [Member] Maximum [Member]	Dec. 31, 2012 Progress Energy Florida [Member]	Dec. 31, 2011 Progress Energy Florida [Member]	Dec. 31, 2010 Progress Energy Florida [Member]	Dec. 31, 2012 Progress Energy Florida [Member] Minimum [Member]	Dec. 31, 2012 Progress Energy Florida [Member] Maximum [Member]
Disclosure Environmental Matters Details [Line Items]
Beginning balance	$ 61	$ 88	$ 65			$ 12	$ 13	$ 13			$ 28	$ 50	$ 20			$ 9	$ 11	$ 15			$ 23	$ 35	$ 42			$ 11	$ 12	$ 13			$ 12	$ 23	$ 29
Amounts accrued for environmental loss contingencies	39	6	37			1					5	5	39			3	1	(2)			19	10	21			5	1	3			14	9	18
Expenditures for environmental loss contingencies	(25)	(33)	(14)			(1)	(1)				(18)	(27)	(9)			(4)	(3)	(2)			(9)	(22)	(28)			(2)	(2)	(4)			(7)	(20)	(24)
Ending balance	75	61	88			12	12	13			15	28	50			8	9	11			33	23	35			14	11	12			19	12	23
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