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	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amounts acquired in Progress Energy merger	$ 29
Progress Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	(24)	(36)	(39)
Revenue, regulated electric	1
Issuances	(16)
Settlements	4
Total gains (losses) included on the Condensed Consolidated Balance Sheet as regulatory asset or liability	(3)	(21)	(44)
Repurchase of CVOs under settlement and tender offer		60
Transfers in and/or out of level 3		33	47
Fair Value, Level 3 Transfers out		14
Fair Value, Level 3 Transfers in		(74)
Ending balance	(38)	(24)	(36)
Progress Energy Carolinas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	(24)	(36)	(27)
Revenue, regulated electric	1
Issuances	(16)
Settlements	4
Total gains (losses) included on the Condensed Consolidated Balance Sheet as regulatory asset or liability	(3)	(20)	(27)
Fair Value, Level 3 Transfers out		32	18
Ending balance	(38)	(24)	(36)
Progress Energy Florida [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance		0	(12)
Total gains (losses) included on the Condensed Consolidated Balance Sheet as regulatory asset or liability		(1)	(17)
Transfers in and/or out of level 3			29
Fair Value, Level 3 Transfers out		1
Ending balance			0
Duke Energy Ohio [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	(3)	13	7
Revenue, regulated electric	1
Revenue, non-regulated electric, natural gas	(4)	(4)	8
Fuel used in electric generation and purchased power - non-regulated			(12)
Losses on commodity cash flow hedges			(1)
Net purchases, sales, issuances, settlements			8
Settlements	1	(14)
Total gains (losses) included on the Condensed Consolidated Balance Sheet as regulatory asset or liability	(1)	2	3
Ending balance	(6)	(3)	13
Revenue, non regulated electric and other - non-regulated			17
Duke Energy Indiana [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	4	4	4
Revenue, regulated electric	36	14
Net purchases, sales, issuances, settlements			(15)
Purchases		8
Sales	22
Settlements	(52)	(21)
Total gains (losses) included on the Condensed Consolidated Balance Sheet as regulatory asset or liability		(1)	15
Ending balance	10	4	4
Available For Sale Auction Rate Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	71	118	198
Gains on available for sale securities and other	13	12	22
Net purchases, sales, issuances, settlements			(102)
Settlements	(55)	(16)
Fair Value, Level 3 Transfers out		(43)
Ending balance	29	71	118
Available For Sale Auction Rate Securities [Member] | Duke Energy Carolinas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	12		66
Gains on available for sale securities and other	2		12
Net purchases, sales, issuances, settlements			(66)
Settlements	(11)
Ending balance	3		12
Available For Sale Ndtf Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	53	47
Net purchases, sales, issuances, settlements			45
Purchases	14	8
Sales	(2)	(3)
Total gains (losses) included on the Condensed Consolidated Balance Sheet as regulatory asset or liability	4	1	2
Ending balance	69	53	47
Available For Sale Ndtf Investments [Member] | Duke Energy Carolinas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	53	47
Net purchases, sales, issuances, settlements			45
Purchases	14	8
Sales	(2)	(3)
Total gains (losses) included on the Condensed Consolidated Balance Sheet as regulatory asset or liability	4	1	2
Ending balance	69	53	47
Derivative [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	(39)	(19)	25
Amounts acquired in Progress Energy merger	(30)
Revenue, regulated electric	23	13
Revenue, non-regulated electric, natural gas	(15)	(27)	(45)
Fuel used in electric generation and purchased power - non-regulated			(13)
Losses on commodity cash flow hedges			(1)
Net purchases, sales, issuances, settlements			(3)
Purchases	22	8
Issuances	(15)
Settlements	(32)	(16)
Total gains (losses) included on the Condensed Consolidated Balance Sheet as regulatory asset or liability	1	2	18
Ending balance	(85)	(39)	(19)
Revenue, regulated electric	(24)
Revenue, non regulated electric and other - non-regulated	1	(20)	1
Derivative [Member] | Duke Energy Carolinas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Issuances	(14)
Settlements	2
Ending balance	(12)
Revenue, regulated electric	(12)
Derivative [Member] | Progress Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Revenue, regulated electric	(12)
Derivative [Member] | Progress Energy Carolinas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Revenue, regulated electric	$ (12)