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														3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Available For Sale Auction Rate Securities [Member]	Mar. 31, 2012 Available For Sale Auction Rate Securities [Member]	Mar. 31, 2013 Available For Sale Ndtf Investments [Member]	Mar. 31, 2012 Available For Sale Ndtf Investments [Member]	Mar. 31, 2013 Derivative [Member]	Mar. 31, 2012 Derivative [Member]	Mar. 31, 2013 Duke Energy Carolinas [Member]	Mar. 31, 2012 Duke Energy Carolinas [Member]	Mar. 31, 2013 Duke Energy Carolinas [Member] Available For Sale Auction Rate Securities [Member]	Dec. 31, 2012 Duke Energy Carolinas [Member] Available For Sale Auction Rate Securities [Member]	Mar. 31, 2012 Duke Energy Carolinas [Member] Available For Sale Auction Rate Securities [Member]	Dec. 31, 2011 Duke Energy Carolinas [Member] Available For Sale Auction Rate Securities [Member]	Mar. 31, 2013 Duke Energy Carolinas [Member] Available For Sale Ndtf Investments [Member]	Mar. 31, 2012 Duke Energy Carolinas [Member] Available For Sale Ndtf Investments [Member]	Mar. 31, 2013 Duke Energy Carolinas [Member] Derivative [Member]	Mar. 31, 2013 Progress Energy [Member]	Mar. 31, 2012 Progress Energy [Member]	Mar. 31, 2013 Duke Energy Progress [Member]	Mar. 31, 2012 Duke Energy Progress [Member]	Mar. 31, 2013 Duke Energy Ohio [Member]	Mar. 31, 2012 Duke Energy Ohio [Member]	Mar. 31, 2013 Duke Energy Indiana [Member]	Mar. 31, 2012 Duke Energy Indiana [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	$ 13	$ 85	$ 29	$ 71	$ 69	$ 53	$ (85)	$ (39)	$ 60	$ 65	$ 3	$ 3	$ 12	$ 12	$ 69	$ 53	$ (12)	$ (38)	$ (24)	$ (38)	$ (24)	$ (6)	$ (3)	$ 10	$ 4
Revenue, regulated electric	(6)	8					(6)	8																(5)	8
Revenue, non-regulated electric, natural gas	(4)	(2)					(4)	(2)														4
Gains on available for sale securities and other	(1)	1	(1)	1
Purchases		2				2				2						2
Issuances	6						6											6		6
Settlements	7	(9)					7	(9)	7								7					(3)			(10)
Total gains (losses) included on the Condensed Consolidated Balance Sheet as regulatory asset or liability	1	1			1	1			1	1					1	1		1	(3)	1	(3)		(1)	(1)	1
Ending balance	16	86	28	72	70	56	(82)	(42)	68	68	3	3	12	12	70	56	(5)	(31)	(27)	(31)	(27)	(5)	(4)	4	3
Revenue, regulated electric	1						1		(5)								(5)	6		6
Revenue, non regulated electric and other - non-regulated	(10)						(10)															(2)	1
Total	$ (9)						$ (9)		$ (5)								$ (5)	$ 6		$ 6		$ (2)	$ 1