Business Segments (Business Segment Data) (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
	Oct. 03, 2016	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues		$ 5,799	$ 6,482	$ 5,555	$ 5,729	$ 5,577	$ 6,576	$ 5,213	$ 5,377	$ 23,565	$ 22,743	$ 22,371
Interest expense										1,986	1,916	1,527
Depreciation and amortization										3,527	3,294	3,053
Equity in earnings (losses) of unconsolidated affiliates										119	(15)	69
Income tax expense (benefit) from continuing operations										1,196	1,156	1,256
Segment income (loss)										3,065	2,571	2,645
Add back noncontrolling interests component										5	7	9
(Loss) Income from Discontinued Operations, net of tax		(2)	(2)	(2)		(598)	180	(112)	122	(6)	(408)	177
Net income (loss)		703	955	689	717	(222)	1,181	512	699	3,064	2,170	2,831
Net Income (Loss) Attributable to Parent		703	954	686	716	(227)	1,176	509	694	3,059	2,152	2,816
Tax Act										(112)
Costs to achieve mergers, integration costs		34	23	30	16					103
Asset Impairment Charges										282	18	106
Costs to achieve mergers, acquisition costs						208	84	111	120		523
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										8,198	13,215	8,363
Segment assets		137,914				132,761				137,914	132,761	121,156
Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues		497	471	437	518	511	489	428	516	1,923	1,944	1,905
Interest expense										91	86	79
Depreciation and amortization										261	233	227
Income tax expense (benefit) from continuing operations										59	78	81
Segment income (loss)										193	192	149
(Loss) Income from Discontinued Operations, net of tax			(1)				34		2	(1)	36	23
Net Income (Loss) Attributable to Parent		65	55	30	42	57	89	23	59	192	228	172
Tax Act		(23)								(23)
Costs to achieve mergers, integration costs		2	2	$ 1	$ 1					6
Asset Impairment Charges										1
Costs to achieve mergers, acquisition costs						2	$ 2	$ 1	$ 1		6
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										686	476	399
Segment assets		7,875				7,528				7,875	7,528	7,097
Piedmont Natural Gas [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net Income (Loss) Attributable to Parent											20
Costs to achieve mergers, integration costs										103	439	9
Asset Impairment Charges										7
Segment Reporting Information Assets [Abstract]
Payments to Acquire Businesses, Gross	$ 5,000
International Energy [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
(Loss) Income from Discontinued Operations, net of tax											(534)	157
Asset Impairment Charges											194
Regulatory settlements [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Regulatory settlement charges		23								158
Asset Impairment Charges			$ 135
Electric Utilities and Infrastructure [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										21,300	21,336	21,489
Equity in earnings (losses) of unconsolidated affiliates										5	5	(2)
Tax Act										231
Electric Utilities and Infrastructure [Member] | Edwardsport IGCC Plant [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Regulatory settlement charges												58
Electric Utilities and Infrastructure [Member] | Regulatory settlements [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Regulatory settlement charges										98
Gas Utilities and Infrastructure [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										1,743	875	536
Equity in earnings (losses) of unconsolidated affiliates										62	19	1
Tax Act										26
Gas Utilities and Infrastructure [Member] | Piedmont Natural Gas [Member]
Segment Reporting Information Assets [Abstract]
Payments to Acquire Businesses, Gross	$ 5,000
Commercial Renewables [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										460	484	286
Equity in earnings (losses) of unconsolidated affiliates										(5)	(82)	(6)
Tax Act										442
Asset Impairment Charges, net of tax										74
Asset Impairment Charges											71
Other Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										62	48	60
Tax Act										597
Costs to achieve mergers, acquisition costs										64	329	60
Cost Savings Initiative, Net of tax											57	77
Other Segments [Member] | International Energy [Member]
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions											26	45
Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										23,503	22,695	22,311
Operating Segments [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										21,331	21,366	21,521
Interest expense										1,240	1,136	1,074
Depreciation and amortization										3,010	2,897	2,735
Equity in earnings (losses) of unconsolidated affiliates										5	5	(2)
Income tax expense (benefit) from continuing operations										1,355	1,672	1,602
Segment income (loss)										3,210	3,040	2,819
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										7,024	6,649	6,852
Segment assets		119,423				114,993				119,423	114,993	109,097
Operating Segments [Member] | Electric Utilities and Infrastructure [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										1,373	1,410	1,331
Interest expense										62	58	53
Depreciation and amortization										178	151	147
Income tax expense (benefit) from continuing operations										40	55	59
Segment income (loss)										138	154	118
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										491	322	264
Segment assets		5,066				4,782				5,066	4,782	4,534
Operating Segments [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										1,836	901	541
Interest expense										105	46	25
Depreciation and amortization										231	115	79
Equity in earnings (losses) of unconsolidated affiliates										62	19	1
Income tax expense (benefit) from continuing operations										116	90	44
Segment income (loss)										319	152	73
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										907	5,519	234
Segment assets		11,462				10,760				11,462	10,760	2,637
Operating Segments [Member] | Gas Utilities and Infrastructure [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										508	503	541
Interest expense										28	27	25
Depreciation and amortization										83	80	79
Income tax expense (benefit) from continuing operations										39	44	45
Segment income (loss)										85	77	73
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										195	154	135
Segment assets		2,758				2,696				2,758	2,696	2,516
Operating Segments [Member] | Commercial Renewables [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										460	484	286
Interest expense										87	53	44
Depreciation and amortization										155	130	104
Equity in earnings (losses) of unconsolidated affiliates										(5)	(82)	(6)
Income tax expense (benefit) from continuing operations										(628)	(160)	(128)
Segment income (loss)										441	23	52
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										92	857	1,019
Segment assets		4,156				4,377				4,156	4,377	3,861
Operating Segments [Member] | Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										23,627	22,751	22,348
Interest expense										1,432	1,235	1,143
Depreciation and amortization										3,396	3,142	2,918
Equity in earnings (losses) of unconsolidated affiliates										62	(58)	(7)
Income tax expense (benefit) from continuing operations										843	1,602	1,518
Segment income (loss)										3,970	3,215	2,944
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										8,023	13,025	8,105
Segment assets		135,041				130,130				135,041	130,130	115,595
Operating Segments [Member] | Total Reportable Segments [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										1,881	1,913	1,872
Interest expense										90	85	78
Depreciation and amortization										261	231	226
Income tax expense (benefit) from continuing operations										79	99	104
Segment income (loss)										223	231	191
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										686	476	399
Segment assets		7,824				7,478				7,824	7,478	7,050
Intersegment Eliminations [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										(200)	(125)	(112)
Interest expense										(20)	(12)	(9)
Segment income (loss)											1
Segment Reporting Information Assets [Abstract]
Segment assets		188				188				188	188	188
Intersegment Eliminations [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Segment income (loss)												(1)
Segment Reporting Information Assets [Abstract]
Segment assets		(15)				(12)				(15)	(12)	(9)
Intersegment Eliminations [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										31	30	32
Intersegment Eliminations [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										93	26	5
Intersegment Eliminations [Member] | Other Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										76	69	75
Intersegment Eliminations [Member] | Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										124	56	37
Corporate, Non-Segment [Member] | Other Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										138	117	135
Interest expense										574	693	393
Depreciation and amortization										131	152	135
Equity in earnings (losses) of unconsolidated affiliates										57	43	76
Income tax expense (benefit) from continuing operations										353	(446)	(262)
Segment income (loss)										(905)	(645)	(299)
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										175	190	258
Segment assets		2,685				2,443				2,685	2,443	5,373
Corporate, Non-Segment [Member] | Other Segments [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										42	31	33
Interest expense										1	1	1
Depreciation and amortization											2	1
Income tax expense (benefit) from continuing operations										(20)	(21)	(23)
Segment income (loss)										(30)	(39)	(41)
Segment Reporting Information Assets [Abstract]
Segment assets		$ 66				$ 62				$ 66	$ 62	$ 56