Fair Value Of Financial Assets And Liabilities (Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended			3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended			9 Months Ended					3 Months Ended	9 Months Ended			3 Months Ended	9 Months Ended			3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Duke Energy Carolinas [Member]	Sep. 30, 2012 Duke Energy Carolinas [Member]	Sep. 30, 2011 Duke Energy Carolinas [Member]	Jun. 30, 2011 Duke Energy Carolinas [Member]	Sep. 30, 2012 Duke Energy Ohio [Member]	Sep. 30, 2011 Duke Energy Ohio [Member]	Sep. 30, 2012 Duke Energy Ohio [Member]	Sep. 30, 2011 Duke Energy Ohio [Member]	Sep. 30, 2012 Duke Energy Indiana [Member]	Sep. 30, 2011 Duke Energy Indiana [Member]	Sep. 30, 2012 Duke Energy Indiana [Member]	Sep. 30, 2011 Duke Energy Indiana [Member]	Sep. 30, 2011 Available-For-Sale Auction Rate Securities [Member]	Sep. 30, 2012 Available-For-Sale Auction Rate Securities [Member]	Sep. 30, 2011 Available-For-Sale Auction Rate Securities [Member]	Jun. 30, 2012 Available-For-Sale Auction Rate Securities [Member]	Sep. 30, 2012 Available-For-Sale Auction Rate Securities [Member] Duke Energy Carolinas [Member]	Jun. 30, 2012 Available-For-Sale Auction Rate Securities [Member] Duke Energy Carolinas [Member]	Sep. 30, 2011 Available-For-Sale Auction Rate Securities [Member] Duke Energy Carolinas [Member]	Jun. 30, 2011 Available-For-Sale Auction Rate Securities [Member] Duke Energy Carolinas [Member]	Dec. 31, 2010 Available-For-Sale Auction Rate Securities [Member] Duke Energy Carolinas [Member]	Sep. 30, 2012 Available-For-Sale NDTF Investments [Member]	Sep. 30, 2012 Available-For-Sale NDTF Investments [Member]	Sep. 30, 2011 Available-For-Sale NDTF Investments [Member]	Jun. 30, 2011 Available-For-Sale NDTF Investments [Member]	Sep. 30, 2012 Available-For-Sale NDTF Investments [Member] Duke Energy Carolinas [Member]	Sep. 30, 2012 Available-For-Sale NDTF Investments [Member] Duke Energy Carolinas [Member]	Sep. 30, 2011 Available-For-Sale NDTF Investments [Member] Duke Energy Carolinas [Member]	Jun. 30, 2011 Available-For-Sale NDTF Investments [Member] Duke Energy Carolinas [Member]	Sep. 30, 2012 Derivatives, Net [Member]	Sep. 30, 2011 Derivatives, Net [Member]	Sep. 30, 2012 Derivatives, Net [Member]	Sep. 30, 2011 Derivatives, Net [Member]	Sep. 30, 2012 Derivatives, Net [Member] Duke Energy Carolinas [Member]	Sep. 30, 2012 Derivatives, Net [Member] Duke Energy Carolinas [Member]
Beginning balance	$ 86	$ 121	$ 85	$ 146	$ 70	$ 65	$ 59	$ 65	$ (2)	$ 7	$ (3)	$ 13	$ 22	$ 10	$ 4	$ 4	$ 90	$ 71	$ 118	$ 41	$ 12	$ 6	$ 12	$ 12	$ 12	$ 64	$ 53	$ 47	$ 53	$ 64	$ 53	$ 47	$ 53	$ (19)	$ (22)	$ (39)	$ (19)
Amounts acquired in Progress Energy merger	(30)		(30)																															(30)		(30)
Revenue, regulated electric	12		37	8					1		1		11	8	35	8																		12		37	8
Revenue, non-regulated electric, natural gas	6	8	9	19					6	1	5	7																						6	8	9	19
Gains on available for sale securities and other		8	9	13		2											8	9	13		2
Purchases	1	8	32	15	1	10	7							8		8										1	10	7		1	10	7			8	22	8
Sales				(3)			(3)								22													(3)				(3)
Issuances	(24)		(24)		(14)	(14)																												(24)		(24)		(14)	(14)
Settlements	(10)	(3)	(73)	(30)	2	(6)			(1)	(1)	1	(2)	(16)	(2)	(45)	(14)	(1)	(39)	(25)		(8)													(10)	(2)	(34)	(5)	2	2
Total gains (losses) included on the Condensed Consolidated Balance Sheet as regulatory asset or liability									(2)		(2)		1	(18)	1	(18)							0											2		2
Fair Value, Level 3 Transfers out		25		(34)													25		(34)
Ending Balance	32	102	32	102	60	60	66	65	(8)	7	(8)	7	17	6	17	6	72	41	72	41	6	6	12	12	12	66	66	54	53	66	66	54	53	(75)	(24)	(75)	(24)	(12)	(12)
Revenue, non regulated electric and other - non-regulated			$ 5	$ (12)							$ 1	$ 1																								$ 5	$ (12)