Investments in Debt and Equity Securities (Available-For-Sale Investments) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012	Jun. 30, 2013		Jun. 30, 2012	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	$ 1,483			$ 1,483			$ 1,216
Gross Unrealized Holding Losses	72			72			30
Estimated Fair Value	5,254			5,254			4,932
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	32		29	63		50
Realized losses	15		0	22		2
Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,462			1,462			1,199
Gross Unrealized Holding Losses	58			58			23
Estimated Fair Value	4,578			4,578			4,263
Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	21	[1]		21	[1]		17	[1]
Gross Unrealized Holding Losses	14	[1]		14	[1]		7	[1]
Estimated Fair Value	676	[1]		676	[1]		669	[1]
Cash and Cash Equivalents [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	91			91			105
Cash and Cash Equivalents [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	19			19			17
Equity Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,418			1,418			1,132
Gross Unrealized Holding Losses	27			27			19
Estimated Fair Value	3,170			3,170			2,837
Equity Securities [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	17			17			10
Gross Unrealized Holding Losses	1			1			0
Estimated Fair Value	78			78			63
Corporate Debt Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	10			10			21
Gross Unrealized Holding Losses	8			8			1
Estimated Fair Value	324			324			338
Corporate Debt Securities [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1			1			2
Gross Unrealized Holding Losses	2			2			0
Estimated Fair Value	334			334			381
Municipal Bonds [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	6			6			12
Gross Unrealized Holding Losses	6			6			1
Estimated Fair Value	205			205			194
Municipal Bonds [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3			3			4
Gross Unrealized Holding Losses	2			2			1
Estimated Fair Value	77			77			70
US Treasury and Government [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	12			12			24
Gross Unrealized Holding Losses	13			13			1
Estimated Fair Value	625			625			625
US Treasury and Government [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains							0
Estimated Fair Value	46			46			23
Auction Rate Securities [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	7			7			6
Estimated Fair Value	26			26			29
Other Debt Obligations [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	16			16			10
Gross Unrealized Holding Losses	4			4			1
Estimated Fair Value	163			163			164
Other Debt Obligations [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	0			0			1
Gross Unrealized Holding Losses	2			2
Estimated Fair Value	96			96			86
Duke Energy Carolinas [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	778			778			632
Gross Unrealized Holding Losses	32			32			9
Estimated Fair Value	2,536			2,536			2,364
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	21		26	46		46
Realized losses	6		0	10		2
Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	778			778			632
Gross Unrealized Holding Losses	31			31			8
Estimated Fair Value	2,533			2,533			2,361
Duke Energy Carolinas [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	1	[2]		1	[2]		1	[2]
Estimated Fair Value	3	[2]		3	[2]		3	[2]
Duke Energy Carolinas [Member] | Cash and Cash Equivalents [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	32			32			40
Duke Energy Carolinas [Member] | Equity Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	754			754			600
Gross Unrealized Holding Losses	13			13			5
Estimated Fair Value	1,763			1,763			1,592
Duke Energy Carolinas [Member] | Corporate Debt Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	5			5			11
Gross Unrealized Holding Losses	6			6			1
Estimated Fair Value	234			234			250
Duke Energy Carolinas [Member] | Municipal Bonds [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	0			0			2
Gross Unrealized Holding Losses	1			1
Estimated Fair Value	42			42			40
Duke Energy Carolinas [Member] | US Treasury and Government [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	4			4			10
Gross Unrealized Holding Losses	7			7
Estimated Fair Value	321			321			304
Duke Energy Carolinas [Member] | Auction Rate Securities [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	1			1			1
Estimated Fair Value	3			3			3
Duke Energy Carolinas [Member] | Other Debt Obligations [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	15			15			9
Gross Unrealized Holding Losses	4			4			2
Estimated Fair Value	141			141			135
Progress Energy [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	687			687			570
Gross Unrealized Holding Losses	28			28			15
Estimated Fair Value	2,104			2,104			1,959
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	10		8	15		15
Realized losses	7		1	9		0
Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	684			684			567
Gross Unrealized Holding Losses	27			27			15
Estimated Fair Value	2,045			2,045			1,902
Progress Energy [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	[1]		3	[1]		3	[1]
Gross Unrealized Holding Losses	1	[1]		1	[1]
Estimated Fair Value	59	[1]		59	[1]		57	[1]
Progress Energy [Member] | Cash and Cash Equivalents [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	59			59			65
Progress Energy [Member] | Cash and Cash Equivalents [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	19			19			17
Progress Energy [Member] | Equity Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	664			664			532
Gross Unrealized Holding Losses	14			14			14
Estimated Fair Value	1,407			1,407			1,245
Progress Energy [Member] | Corporate Debt Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	5			5			9
Gross Unrealized Holding Losses	2			2
Estimated Fair Value	90			90			89
Progress Energy [Member] | Municipal Bonds [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	6			6			11
Gross Unrealized Holding Losses	5			5			1
Estimated Fair Value	163			163			154
Progress Energy [Member] | Municipal Bonds [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3			3			3
Gross Unrealized Holding Losses	1			1
Estimated Fair Value	40			40			40
Progress Energy [Member] | US Treasury and Government [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	8			8			14
Gross Unrealized Holding Losses	6			6
Estimated Fair Value	304			304			321
Progress Energy [Member] | Other Debt Obligations [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1			1			1
Estimated Fair Value	22			22			28
Duke Energy Progress [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	441			441			363
Gross Unrealized Holding Losses	19			19			11
Estimated Fair Value	1,374			1,374			1,278
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	6		5	8		10
Realized losses	3		1	4		3
Duke Energy Progress [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	441			441			363
Gross Unrealized Holding Losses	19			19			11
Estimated Fair Value	1,372			1,372			1,275
Duke Energy Progress [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	2	[1]		2	[1]		3	[1]
Duke Energy Progress [Member] | Cash and Cash Equivalents [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	32			32			55
Duke Energy Progress [Member] | Cash and Cash Equivalents [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	2			2			3
Duke Energy Progress [Member] | Equity Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	425			425			337
Gross Unrealized Holding Losses	10			10			11
Estimated Fair Value	919			919			811
Duke Energy Progress [Member] | Corporate Debt Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	4			4			8
Gross Unrealized Holding Losses	2			2
Estimated Fair Value	80			80			78
Duke Energy Progress [Member] | Municipal Bonds [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3			3			4
Gross Unrealized Holding Losses	4			4
Estimated Fair Value	102			102			80
Duke Energy Progress [Member] | US Treasury and Government [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	8			8			13
Gross Unrealized Holding Losses	3			3
Estimated Fair Value	228			228			241
Duke Energy Progress [Member] | Other Debt Obligations [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1			1			1
Estimated Fair Value	11			11			10
Duke Energy Florida [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	246			246			207
Gross Unrealized Holding Losses	8			8			4
Estimated Fair Value	716			716			668
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	5		3	8		5
Realized losses	3		2	4		3
Duke Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	243			243			204
Gross Unrealized Holding Losses	8			8			4
Estimated Fair Value	673			673			627
Duke Energy Florida [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	[3]		3	[3]		3	[3]
Estimated Fair Value	43	[3]		43	[3]		41	[3]
Duke Energy Florida [Member] | Cash and Cash Equivalents [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	27			27			10
Duke Energy Florida [Member] | Cash and Cash Equivalents [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	3			3			1
Duke Energy Florida [Member] | Equity Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	239			239			194
Gross Unrealized Holding Losses	4			4			4
Estimated Fair Value	488			488			434
Duke Energy Florida [Member] | Corporate Debt Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1			1			1
Estimated Fair Value	10			10			11
Duke Energy Florida [Member] | Municipal Bonds [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3			3			7
Gross Unrealized Holding Losses	1			1			0
Estimated Fair Value	61			61			74
Duke Energy Florida [Member] | Municipal Bonds [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3			3			3
Estimated Fair Value	40			40			40
Duke Energy Florida [Member] | US Treasury and Government [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	0			0			1
Gross Unrealized Holding Losses	3			3
Estimated Fair Value	76			76			80
Duke Energy Florida [Member] | Other Debt Obligations [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	0			0			1
Estimated Fair Value	11			11			18
Duke Energy Indiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	15			15			10
Gross Unrealized Holding Losses	1			1			0
Estimated Fair Value	84			84			78
Duke Energy Indiana [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	15	[1]		15	[1]		10	[1]
Gross Unrealized Holding Losses	1	[1]		1	[1]		0	[1]
Estimated Fair Value	84	[1]		84	[1]		78	[1]
Duke Energy Indiana [Member] | Equity Securities [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	15			15			9
Gross Unrealized Holding Losses							0
Estimated Fair Value	56			56			50
Duke Energy Indiana [Member] | Municipal Bonds [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	0			0			1
Gross Unrealized Holding Losses	1			1
Estimated Fair Value	$ 28			$ 28			$ 28

[1] These amounts are recorded in Other within Investments and Other Assets on the Condensed Consolidated Balance Sheets.

[2] These amounts are recorded in Other within Investments and Other Assets on the Condensed Consolidated Balance Sheets.

[3] These amounts are recorded in Other within Investments and Other Assets on the Condensed Balance sheets.