Investments in Debt and Equity Securities (Available-For-Sale Investments) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended			12 Months Ended
	Sep. 30, 2013		Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				$ 1,630			$ 1,216
Gross Unrealized Holding Losses				50			30
Estimated Fair Value	5,323			5,323			4,932
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	72		30	135		80
Realized losses	16		12	38		14
Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				1,605			1,199
Gross Unrealized Holding Losses				38			23
Estimated Fair Value	4,806			4,806			4,263
Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				25	[1]		17	[1]
Gross Unrealized Holding Losses				12	[1]		7	[1]
Estimated Fair Value	517	[1]		517	[1]		669	[1]
Cash and Cash Equivalents [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	111			111			105
Cash and Cash Equivalents [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	21			21			17
Equity Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				1,560			1,132
Gross Unrealized Holding Losses				13			19
Estimated Fair Value	3,280			3,280			2,837
Equity Securities [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				22			10
Estimated Fair Value	83			83			63
Corporate Debt Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				9			21
Gross Unrealized Holding Losses				6			1
Estimated Fair Value	323			323			338
Corporate Debt Securities [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				1			2
Gross Unrealized Holding Losses				2
Estimated Fair Value	178			178			381
Municipal Bonds [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				5			12
Gross Unrealized Holding Losses				7			1
Estimated Fair Value	213			213			194
Municipal Bonds [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				2			4
Gross Unrealized Holding Losses				2			1
Estimated Fair Value	80			80			70
US Treasury and Government [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				14			24
Gross Unrealized Holding Losses				8			1
Estimated Fair Value	712			712			625
US Treasury and Government [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	38			38			23
Auction Rate Securities [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses				7			6
Estimated Fair Value	25			25			29
Other Debt Obligations [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				17			10
Gross Unrealized Holding Losses				4			1
Estimated Fair Value	167			167			164
Other Debt Obligations [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains							1
Gross Unrealized Holding Losses				1
Estimated Fair Value	92			92			86
Duke Energy Carolinas [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				854			632
Gross Unrealized Holding Losses				20			9
Estimated Fair Value	2,670			2,670			2,364
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	49		19	95		65
Realized losses	1		5	11		7
Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				854			632
Gross Unrealized Holding Losses				19			8
Estimated Fair Value	2,667			2,667			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]
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	46			46			40
Duke Energy Carolinas [Member] | Equity Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				828			600
Gross Unrealized Holding Losses				5			5
Estimated Fair Value	1,790			1,790			1,592
Duke Energy Carolinas [Member] | Corporate Debt Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				4			11
Gross Unrealized Holding Losses				5			1
Estimated Fair Value	236			236			250
Duke Energy Carolinas [Member] | Municipal Bonds [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains							2
Gross Unrealized Holding Losses				1
Estimated Fair Value	52			52			40
Duke Energy Carolinas [Member] | US Treasury and Government [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				5			10
Gross Unrealized Holding Losses				4
Estimated Fair Value	396			396			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
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				17			9
Gross Unrealized Holding Losses				4			2
Estimated Fair Value	147			147			135
Progress Energy [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				752			570
Gross Unrealized Holding Losses				20			15
Estimated Fair Value	2,196			2,196			1,959
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	22		8	37		23
Realized losses	11		6	20		12
Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				751			567
Gross Unrealized Holding Losses				19			15
Estimated Fair Value	2,139			2,139			1,902
Progress Energy [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				1	[1]		3	[1]
Gross Unrealized Holding Losses				1	[1]
Estimated Fair Value	57	[1]		57	[1]		57	[1]
Progress Energy [Member] | Cash and Cash Equivalents [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	65			65			65
Progress Energy [Member] | Cash and Cash Equivalents [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	21			21			17
Progress Energy [Member] | Equity Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				732			532
Gross Unrealized Holding Losses				8			14
Estimated Fair Value	1,490			1,490			1,245
Progress Energy [Member] | Corporate Debt Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				5			9
Gross Unrealized Holding Losses				1
Estimated Fair Value	87			87			89
Progress Energy [Member] | Municipal Bonds [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				5			11
Gross Unrealized Holding Losses				6			1
Estimated Fair Value	161			161			154
Progress Energy [Member] | Municipal Bonds [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				1			3
Gross Unrealized Holding Losses				1
Estimated Fair Value	36			36			40
Progress Energy [Member] | US Treasury and Government [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				9			14
Gross Unrealized Holding Losses				4
Estimated Fair Value	316			316			321
Progress Energy [Member] | Other Debt Obligations [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains							1
Estimated Fair Value	20			20			28
Duke Energy Progress [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				487			363
Gross Unrealized Holding Losses				15			11
Estimated Fair Value	1,437			1,437			1,278
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	7		4	15		14
Realized losses	2		2	6		5
Duke Energy Progress [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				487			363
Gross Unrealized Holding Losses				15			11
Estimated Fair Value	1,435			1,435			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	30			30			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				472			337
Gross Unrealized Holding Losses				7			11
Estimated Fair Value	985			985			811
Duke Energy Progress [Member] | Corporate Debt Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				5			8
Gross Unrealized Holding Losses				1
Estimated Fair Value	83			83			78
Duke Energy Progress [Member] | Municipal Bonds [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				2			4
Gross Unrealized Holding Losses				4
Estimated Fair Value	103			103			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			13
Gross Unrealized Holding Losses				3
Estimated Fair Value	225			225			241
Duke Energy Progress [Member] | Other Debt Obligations [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains							1
Estimated Fair Value	9			9			10
Duke Energy Florida [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				265			207
Gross Unrealized Holding Losses				5			4
Estimated Fair Value	745			745			668
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	14		4	22		9
Realized losses	9		4	13		7
Duke Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				264			204
Gross Unrealized Holding Losses				4			4
Estimated Fair Value	704			704			627
Duke Energy Florida [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				1	[3]		3	[3]
Gross Unrealized Holding Losses				1	[3]
Estimated Fair Value	41	[3]		41	[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	35			35			10
Duke Energy Florida [Member] | Cash and Cash Equivalents [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	4			4			1
Duke Energy Florida [Member] | Equity Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				260			194
Gross Unrealized Holding Losses				1			4
Estimated Fair Value	505			505			434
Duke Energy Florida [Member] | Corporate Debt Securities [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains							1
Estimated Fair Value	4			4			11
Duke Energy Florida [Member] | Municipal Bonds [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				3			7
Gross Unrealized Holding Losses				2
Estimated Fair Value	58			58			74
Duke Energy Florida [Member] | Municipal Bonds [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				1			3
Gross Unrealized Holding Losses				1
Estimated Fair Value	37			37			40
Duke Energy Florida [Member] | US Treasury and Government [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				1			1
Gross Unrealized Holding Losses				1
Estimated Fair Value	91			91			80
Duke Energy Florida [Member] | Other Debt Obligations [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains							1
Estimated Fair Value	11			11			18
Duke Energy Indiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				19			10
Gross Unrealized Holding Losses				1
Estimated Fair Value	88			88			78
Duke Energy Indiana [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains				19	[1]		10	[1]
Gross Unrealized Holding Losses				1	[1]
Estimated Fair Value	88	[1]		88	[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				19			9
Estimated Fair Value	60			60			50
Duke Energy Indiana [Member] | Municipal Bonds [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains							1
Gross Unrealized Holding Losses				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.