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		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended				3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Duke Energy Carolinas [Member]	Jun. 30, 2011 Duke Energy Carolinas [Member]	Jun. 30, 2012 Duke Energy Carolinas [Member]	Jun. 30, 2011 Duke Energy Carolinas [Member]	Jun. 30, 2012 Available-For-Sale Auction Rate Securities [Member]	Jun. 30, 2011 Available-For-Sale Auction Rate Securities [Member]	Jun. 30, 2012 Available-For-Sale Auction Rate Securities [Member]	Jun. 30, 2011 Available-For-Sale Auction Rate Securities [Member]	Jun. 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]	Jun. 30, 2011 Available-For-Sale Auction Rate Securities [Member] Duke Energy Carolinas [Member]	Mar. 31, 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]	Jun. 30, 2012 Available-For-Sale NDTF Investments [Member]	Jun. 30, 2011 Available-For-Sale NDTF Investments [Member]	Jun. 30, 2012 Available-For-Sale NDTF Investments [Member]	Jun. 30, 2011 Available-For-Sale NDTF Investments [Member]	Jun. 30, 2012 Available-For-Sale NDTF Investments [Member] Duke Energy Carolinas [Member]	Jun. 30, 2011 Available-For-Sale NDTF Investments [Member] Duke Energy Carolinas [Member]	Jun. 30, 2012 Available-For-Sale NDTF Investments [Member] Duke Energy Carolinas [Member]	Jun. 30, 2011 Available-For-Sale NDTF Investments [Member] Duke Energy Carolinas [Member]	Jun. 30, 2012 Derivatives, Net [Member]	Jun. 30, 2011 Derivatives, Net [Member]	Jun. 30, 2012 Derivatives, Net [Member]	Jun. 30, 2011 Derivatives, Net [Member]	Jun. 30, 2012 Derivatives, Net [Member] Duke Energy Ohio [Member]	Jun. 30, 2011 Derivatives, Net [Member] Duke Energy Ohio [Member]	Jun. 30, 2012 Derivatives, Net [Member] Duke Energy Ohio [Member]	Jun. 30, 2011 Derivatives, Net [Member] Duke Energy Ohio [Member]	Jun. 30, 2012 Derivatives, Net [Member] Duke Energy Indiana [Member]	Jun. 30, 2011 Derivatives, Net [Member] Duke Energy Indiana [Member]	Jun. 30, 2012 Derivatives, Net [Member] Duke Energy Indiana [Member]	Jun. 30, 2011 Derivatives, Net [Member] Duke Energy Indiana [Member]
Beginning balance	$ 86	$ 146	$ 85	$ 146	$ 68	$ 60	$ 65	$ 59	$ 72	$ 122	$ 71	$ 118	$ 12	$ 12	$ 12	$ 12	$ 12	$ 56	$ 48	$ 53	$ 47	$ 56	$ 48	$ 53	$ 47	$ (42)	$ (24)	$ (39)	$ (19)	$ (4)	$ 17	$ (3)	$ 13	$ 3	$ 1	$ 4	$ 4
Revenue, regulated electric	17		25																							17		25						16		24
Revenue, non-regulated electric, natural gas	(1)	(11)	(3)	(19)																						(1)	(11)	(3)	(19)	(1)	(10)	(1)	(6)
Gains on available for sale securities and other	8	(1)	9	5	2		2		8	(1)	9	5	2	2
Purchases	29	6	31	7	7	6	9	7										7	6	9	7	7	6	9	7	22		22
Sales		(1)		(3)		(1)		(3)											(1)		(3)		(1)		(3)									(22)		(22)
Settlements	(54)	(28)	(63)	(27)	(8)		(8)		(39)	(22)	(39)	(24)	(8)	(8)												(15)	(6)	(24)	(3)	(2)		(2)	(1)	(19)	(10)	(29)	(12)
Total gains (losses) included on the Condensed Consolidated Balance Sheet as regulatory asset or liability	1	19	2	21	1		2	2										1		2	2	1		2	2		19		19	(1)		(2)	1		19	1	18
Fair Value, Level 3 Transfers out		(9)		(9)						(9)		(9)
Ending Balance	86	121	86	121	70	65	70	65	41	90	41	90	6	6	12	12	12	64	53	64	53	64	53	64	53	(19)	(22)	(19)	(22)	(2)	7	(2)	7	22	10	22	10
Revenue, non regulated electric and other - non-regulated			$ (3)	$ (10)																								$ (3)	$ (10)			$ 1	$ 1