Business Segments (Business Segment Data) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	$ 6,483	$ 6,395	$ 18,137	$ 18,366
Segment income	937	888	2,310	2,356
Add back noncontrolling interests	3	3	10	11
(Loss) Income From Discontinued Operations, net of tax	(5)	378	29	(578)
Net income (loss) attributable to parent	932	1,274	2,339	1,786
Net income (loss)	935	1,269	2,349	1,789
Segment assets	121,033		121,033		$ 120,709
Impairment charges	111	1	111	81
Charge for settlement agreement, net of tax			53
Regulated Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	6,138	5,975	17,062	17,041
International Energy [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	281	366	841	1,111
Commercial Portfolio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	66	50	214	195
State Tax Charge			41
Other [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	(2)	4	20	19
Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	6,485	6,391	18,117	18,347
Operating Segments [Member] | Regulated Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	6,147	5,986	17,090	17,074
Segment income	905	920	2,311	2,346
Segment assets	110,520		110,520
Operating Segments [Member] | International Energy [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	281	366	841	1,111
Segment income	69	80	157	356
Segment assets	3,730		3,730
Operating Segments [Member] | Commercial Portfolio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	66	50	214	195
Segment income	(3)	(17)	(35)	(70)
Segment assets	3,841		3,841
Operating Segments [Member] | Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	6,494	6,402	18,145	18,380
Segment income	971	983	2,433	2,632
Segment assets	118,091		118,091
Intersegment Eliminations [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	(28)	(32)	(86)	(93)
Segment income		(3)	(4)	(7)
Segment assets	185		185
Intersegment Eliminations [Member] | Regulated Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	(9)	(11)	(28)	(33)
Intersegment Eliminations [Member] | Other [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	(19)	(21)	(58)	(60)
Intersegment Eliminations [Member] | Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	(9)	(11)	(28)	(33)
Corporate, Non-Segment [Member] | Other [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	17	25	78	79
Segment income	(34)	(92)	(119)	(269)
Segment assets	2,757		2,757
Costs to achieve Progress Energy merger	15	35	42	107
Other VIEs [Member] | Commercial Portfolio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Impairment charges				94
Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	462	446	1,453	1,433
Segment income	34	26	106	39
(Loss) Income From Discontinued Operations, net of tax	(2)	413	23	(597)
Net income (loss) attributable to parent	32	439	129	(558)
Segment assets	7,083		7,083		9,999
Impairment charges				94
Charge for settlement agreement, net of tax			53
Duke Energy Ohio [Member] | Regulated Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues		440		1,416
Duke Energy Ohio [Member] | Commercial Portfolio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues		6		17
Duke Energy Ohio [Member] | Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues		446		1,433
Duke Energy Ohio [Member] | Operating Segments [Member] | Regulated Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	456	441	1,424	1,417
Segment income	46	43	135	151
Segment assets	6,961		6,961
Duke Energy Ohio [Member] | Operating Segments [Member] | Commercial Portfolio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues		6	14	17
Segment income		(13)	(9)	(101)
Duke Energy Ohio [Member] | Operating Segments [Member] | Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues		447	1,438	1,434
Segment income		30	126	50
Duke Energy Ohio [Member] | Intersegment Eliminations [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues		(1)		(1)
Segment assets	(4)		(4)
Duke Energy Ohio [Member] | Intersegment Eliminations [Member] | Regulated Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues		(1)		(1)
Duke Energy Ohio [Member] | Intersegment Eliminations [Member] | Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues		(1)		(1)
Duke Energy Ohio [Member] | Corporate, Non-Segment [Member] | Other [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	6		15
Segment income	(12)	$ (4)	(20)	(11)
Segment assets	126		126
Duke Energy Ohio [Member] | Other VIEs [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Impairment charges				94	$ 94
Duke Energy Ohio [Member] | Other VIEs [Member] | Commercial Portfolio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Impairment charges				$ 94
Edwardsport Igcc Plant [Member] | Regulated Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Impairment charges	$ 56		$ 56