Business Segments (Business Segment Data) (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
Segment Reporting Information, Profit (Loss) [Abstract]
Unaffiliated Revenues	$ 5,879	[1],[2]	$ 3,577	$ 11,777	[1],[3]	$ 7,207	[4]
Intersegment Revenues				0
Operating revenues	5,879		3,577	11,777		7,207
Segment income	342	[1],[2],[5],[6],[7]	445	976	[1],[3],[5],[8],[9]	738	[10],[4]
Add back Noncontrolling interest component	3		4	3		8
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(3)		(1)	(3)		1
Net Income (Loss)	342		448	976		747
Segment Reporting Information Assets [Abstract]
Segment assets	114,100			114,100				113,856
U S Franchised Electric And Gas [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Unaffiliated Revenues	4,911	[1],[2]	2,688	9,963	[1],[3]	5,348	[4]
Intersegment Revenues	9		9	17		17
Segment Reporting Information, Revenue for Reportable Segment, Total	4,920		2,697	9,980		5,365
Segment income	353	[1],[2],[5],[6]	337	1,009	[1],[3],[5],[8]	473	[10],[4]
Segments Notes To Tables [Abstract]
After-tax deferral of voluntary severance program expense						60
Deferral of voluntary severance program expense, tax						39
Segment Reporting Information Assets [Abstract]
Segment assets	98,908			98,908
U S Franchised Electric And Gas [Member] | Edwardsport IGCC Plant [Member]
Segments Notes To Tables [Abstract]
After-tax impairment charge						268
Impairment charge, tax						152
U S Franchised Electric And Gas [Member] | North Carolina Rate Case [Member]
Segments Notes To Tables [Abstract]
Approved rate increase amount by state commission						309
U S Franchised Electric And Gas [Member] | South Carolina Rate Case [Member]
Segments Notes To Tables [Abstract]
Approved rate increase amount by state commission						93
Commercial Power [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Unaffiliated Revenues	547		488	986		1,052
Intersegment Revenues	10		14	23		30
Segment Reporting Information, Revenue for Reportable Segment, Total	557		502	1,009		1,082
Segment income	41		28	(1)		59
Segment Reporting Information Assets [Abstract]
Segment assets	6,907			6,907
International Energy [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Unaffiliated Revenues	406		397	798		799
Intersegment Revenues				0
Segment Reporting Information, Revenue for Reportable Segment, Total	406		397	798		799
Segment income	87		105	184		247
Segment Reporting Information Assets [Abstract]
Segment assets	5,480			5,480
Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Unaffiliated Revenues	5,864	[1],[2]	3,573	11,747	[1],[3]	7,199	[4]
Intersegment Revenues	19		23	40		47
Segment Reporting Information, Revenue for Reportable Segment, Total	5,883		3,596	11,787		7,246
Segment income	481	[1],[2],[5],[6]	470	1,192	[1],[3],[5],[8]	779	[10],[4]
Segment Reporting Information Assets [Abstract]
Segment assets	111,295			111,295
All Other Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Unaffiliated Revenues	15		4	30		8
Intersegment Revenues	21		12	41		23
Segment Reporting Information, Revenue for Reportable Segment, Total	36		16	71		31
Segment income	(139)	[7]	(25)	(216)	[9]	(41)
Segments Notes To Tables [Abstract]
After-tax costs to achieve the merger	51			85
Costs to achieve the merger, tax	31			52
Segment Reporting Information Assets [Abstract]
Segment assets	2,663			2,663
Intersegment Eliminations [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Intersegment Revenues	(40)		(35)	(81)		(70)
Segment Reporting Information, Revenue for Reportable Segment, Total	(40)		(35)	(81)		(70)
Segment Reporting Information Assets [Abstract]
Segment assets	142			142
Duke Energy Carolinas [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	1,591		1,616	3,320		3,117
Net Income (Loss)	181		211	425		477
Segment Reporting Information Assets [Abstract]
Segment assets	31,017			31,017				30,642
Duke Energy Carolinas [Member] | All Other Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Segment income	(25)		(11)	(43)		(18)
Progress Energy [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	2,281		2,288	4,467		4,390
Add back Noncontrolling interest component	0		1	1		3
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(4)		(4)	(4)		7
Net Income (Loss)	(17)		64	137		216
Segment Reporting Information Assets [Abstract]
Segment assets	37,551			37,551				37,405
Progress Energy [Member] | All Other Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Segment income	(55)		(58)	(133)		(97)
Duke Energy Progress [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	1,135		1,090	2,351		2,180
Net Income (Loss)	77		31	187		83
Segment Reporting Information Assets [Abstract]
Segment assets	18,605			18,605				18,068
Duke Energy Progress [Member] | Rate Case Phase One [Member] | NCUC [Member]
Segments Notes To Tables [Abstract]
Approved rate increase amount by state commission				147
Duke Energy Progress [Member] | U S Franchised Electric And Gas [Member] | Rate Case Phase One [Member] | NCUC [Member]
Segments Notes To Tables [Abstract]
Approved rate increase amount by state commission	147			147
Duke Energy Progress [Member] | U S Franchised Electric And Gas [Member] | Shearon Harris Nuclear Station [Member]
Segments Notes To Tables [Abstract]
After-tax public utilities, property, plant and equipment, amount of indirect disallowance of costs of recently completed plants	13			13
Public utilities, property, plant and equipment, amount of indirect disallowance of costs of recently completed plants, tax	9			9
Duke Energy Progress [Member] | All Other Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Segment income	(14)		(7)	(20)		(9)
Duke Energy Florida [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	1,142		1,196	2,110		2,206
Net Income (Loss)	(57)		83	53		211
Segment Reporting Information Assets [Abstract]
Segment assets	14,792			14,792				15,180
Duke Energy Florida [Member] | U S Franchised Electric And Gas [Member] | Crystal River Unit 3 [Member] | 2013 FPSC Settlement Agreement [Member] | FPSC [Member]
Segments Notes To Tables [Abstract]
After-tax impairment charge	180			180
Impairment charge, tax	115			115
Duke Energy Florida [Member] | U S Franchised Electric And Gas [Member] | Levy Nuclear Station [Member] | 2013 FPSC Settlement Agreement [Member] | FPSC [Member]
Segments Notes To Tables [Abstract]
After-tax impairment charge	44			44
Impairment charge, tax	21			21
Duke Energy Florida [Member] | All Other Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Segment income	(7)		(5)	(12)		(7)
Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Unaffiliated Revenues	811	[11]	717	1,558	[11]	1,629
Operating revenues	811		717	1,558		1,629
Segment income	58	[11]	45	37	[11]	119
Net Income (Loss)	58		45	37		119
Segment Reporting Information Assets [Abstract]
Segment assets	10,606			10,606				10,560
Duke Energy Ohio [Member] | Electric Rate Case [Member] | PUCO [Member]
Segments Notes To Tables [Abstract]
Approved rate increase amount by state commission				49
Duke Energy Ohio [Member] | U S Franchised Electric And Gas [Member] | Electric Rate Case [Member] | PUCO [Member]
Segments Notes To Tables [Abstract]
Approved rate increase amount by state commission	49			49
Duke Energy Ohio [Member] | Franchised Electric & Gas [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Unaffiliated Revenues	404	[11]	387	896	[11]	860
Intersegment Revenues	0			0
Segment Reporting Information, Revenue for Reportable Segment, Total	404		387	896		860
Segment income	27	[11]	30	80	[11]	64
Segment Reporting Information Assets [Abstract]
Segment assets	6,568			6,568
Duke Energy Ohio [Member] | Franchised Electric & Gas [Member] | Electric Rate Case [Member] | PUCO [Member]
Segments Notes To Tables [Abstract]
Approved rate increase amount by state commission	49			49
Duke Energy Ohio [Member] | DEO Commercial Power [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Unaffiliated Revenues	407		330	662		769
Intersegment Revenues	8		12	19		27
Segment Reporting Information, Revenue for Reportable Segment, Total	415		342	681		796
Segment income	35		17	(33)		61
Segment Reporting Information Assets [Abstract]
Segment assets	4,116			4,116
Duke Energy Ohio [Member] | Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Unaffiliated Revenues	811	[11]	717	1,558	[11]	1,629
Intersegment Revenues	8		12	19		27
Segment Reporting Information, Revenue for Reportable Segment, Total	819		729	1,577		1,656
Segment income	62	[11]	47	47	[11]	125
Segment Reporting Information Assets [Abstract]
Segment assets	10,684			10,684
Duke Energy Ohio [Member] | All Other Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Unaffiliated Revenues				0
Intersegment Revenues				0
Segment Reporting Information, Revenue for Reportable Segment, Total				0
Segment income	(4)		(2)	(10)		(6)
Segment Reporting Information Assets [Abstract]
Segment assets	100			100
Duke Energy Ohio [Member] | Intersegment Eliminations [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Unaffiliated Revenues	0		0	0
Intersegment Revenues	(8)		(12)	(19)		(27)
Segment Reporting Information, Revenue for Reportable Segment, Total	(8)		(12)	(19)		(27)
Segment Reporting Information Assets [Abstract]
Segment assets	(178)			(178)
Duke Energy Indiana [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	700		685	1,424		1,373
Net Income (Loss)	82		77	172		(90)
Segment Reporting Information Assets [Abstract]
Segment assets	10,124			10,124				10,008
Duke Energy Indiana [Member] | All Other Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Segment income	$ (4)		$ (1)	$ (8)		$ (5)

[1] On May 1, 2013, the PUCO approved a Duke Energy Ohio settlement agreement that provides for a net annual increase in electric distribution revenues of $49 million, beginning in May 2013. This rate increase impacts USFE&G.

[2] On May 30, 2013, the NCUC approved a Duke Energy Progress settlement agreement that included a $147 million increase in rates in the first year, beginning on June 1, 2013. This rate increase impacts USFE&G.

[3] On May 30, 2013, the NCUC approved a Duke Energy Progress settlement agreement that included a $147 million increase in rates in the first year, beginning on June 1, 2013. This rate increase impacts USFE&G.

[4] On January 25, 2012 and January 27, 2012, the Duke Energy Carolinas' South Carolina and North Carolina rate case settlement agreements were approved by the PSCSC and NCUC, respectively. Among other things, the rate case settlements included an annual base rate increase of $309 million in North Carolina and a $93 million annual base rate increase in South Carolina, both beginning in February 2012. These rate increases impact USFE&G.

[5] USFE&G recorded an after-tax impairment charge of $180 million, net of tax of $115 million, related to Duke Energy Florida's Crystal River Unit 3. See Note 4 for additional information.

[6] USFE&G recorded an after-tax impairment charge of $13 million, net of tax of $9 million, related to the letter Duke Energy Progress filed with the NRC requesting the NRC to suspend its review activities associated with the combined construction and operating license (COL) at the Shearon Harris Nuclear Station (Harris) site. USFE&G also recorded an after-tax impairment charge of $44 million, net of tax of $21 million, related to the write-off of the wholesale portion of Levy investments at Duke Energy Florida in accordance with the 2013 Settlement. See Note 4 for additional information.

[7] Other includes after-tax costs to achieve the merger with Progress Energy of $51 million, net of tax of $31 million. See Note 2 for additional information about the merger.

[8] USFE&G recorded an after-tax impairment charge of $13 million, net of tax of $9 million, related to the letter Duke Energy Progress filed with the NRC requesting the NRC to suspend its review activities associated with the combined construction and operating license (COL) at the Shearon Harris Nuclear Station (Harris) site. USFE&G also recorded an after-tax impairment charge of $44 million, net of tax of $21 million, related to the write-off of the wholesale portion of Levy investments at Duke Energy Florida in accordance with the 2013 Settlement. See Note 4 for additional information.

[9] Other includes after-tax costs to achieve the merger with Progress Energy of $85 million, net of tax of $52 million. See Note 2 for additional information about the merger.

[10] USFE&G recorded an after-tax impairment charge of $268 million, net of tax of $152 million, related to Duke Energy Indiana's Edwardsport Integrated Gasification Combined Cycle (IGCC) project. USFE&G also recorded the reversal of expenses of $60 million, net of tax of $39 million, related to a prior year Voluntary Opportunity Plan in accordance with Duke Energy Carolinas' 2011 rate case.

[11] On May 1, 2013, the PUCO approved a Duke Energy Ohio settlement agreement that provides for a net annual increase in electric distribution revenues of $49 million, beginning in May 2013. This rate increase impacts Franchised Electric and Gas.