Business Segments (Business Segment Data) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Operating revenues	$ 6,628	$ 6,482	$ 18,406	$ 17,766
Segment income (loss)	1,078	956	2,203	2,360
Add back noncontrolling interests	(16)	1	(12)	5
Income (Loss) From Discontinued Operations, net of tax	4	(2)	(1)	(4)
Net Income	1,066	955	2,190	2,361
Net income (attributable to parent)	1,082	954	2,202	2,356
Segment assets	143,165		143,165		$ 137,914
Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	6,253	6,122	16,783	16,211
Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	232	249	1,229	1,175
Commercial Renewables [Member]
Segment Reporting Information [Line Items]
Operating revenues	127	95	347	333
Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	6,612	6,466	18,359	17,719
Other [Member]
Segment Reporting Information [Line Items]
Operating revenues	16	16	47	47
Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment income (loss)	1,122	990	2,649	2,565
Segment assets	139,865		139,865
Operating Segments [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	6,260	6,129	16,806	16,234
Segment income (loss)	1,167	1,020	2,492	2,384
Segment assets	123,847		123,847
Operating Segments [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	256	272	1,301	1,243
Segment income (loss)	17	19	161	179
Segment assets	11,806		11,806
Operating Segments [Member] | Commercial Renewables [Member]
Segment Reporting Information [Line Items]
Operating revenues	127	95	347	333
Segment income (loss)	(62)	(49)	(4)	2
Segment assets	4,212		4,212
Operating Segments [Member] | Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	6,643	6,496	18,454	17,810
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues	(49)	(49)	(149)	(147)
Segment assets	185		185
Intersegment Eliminations [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	7	7	23	23
Intersegment Eliminations [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	24	23	72	68
Intersegment Eliminations [Member] | Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	31	30	95	91
Intersegment Eliminations [Member] | Other [Member]
Segment Reporting Information [Line Items]
Operating revenues	18	19	54	56
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Segment income (loss)	(44)	(34)	(446)	(205)
Segment assets	3,115		3,115
Corporate, Non-Segment [Member] | Other [Member]
Segment Reporting Information [Line Items]
Operating revenues	34	35	101	103
Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Operating revenues	469	471	1,452	1,426
Segment income (loss)	100	56	121	128
Income (Loss) From Discontinued Operations, net of tax		(1)		(1)
Net Income				127
Net income (attributable to parent)	100	55	121	127
Segment assets	8,296		8,296		$ 7,875
Duke Energy Ohio [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	373	371	1,055	1,036
Duke Energy Ohio [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	84	90	361	360
Duke Energy Ohio [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	457	461	1,416	1,396
Segment income (loss)	97	64	221	152
Segment assets	8,259		8,259
Duke Energy Ohio [Member] | Operating Segments [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Segment income (loss)	85	50	157	96
Segment assets	5,484		5,484
Duke Energy Ohio [Member] | Operating Segments [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Segment income (loss)	12	14	64	56
Segment assets	2,775		2,775
Duke Energy Ohio [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Segment assets	(2)		(2)
Duke Energy Ohio [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	12	10	36	30
Segment income (loss)	3	$ (8)	(100)	$ (24)
Segment assets	$ 39		$ 39