Business Segments (Business Segment Data) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Operating revenues	$ 5,643	$ 5,555	$ 11,778	$ 11,284
Segment income (loss)	505	688	1,125	1,404
Net Income (Loss) Attributable to Noncontrolling Interest	2	3	4	4
Loss From Discontinued Operations, net of tax	(5)	(2)	(5)	(2)
Net income	502	689	1,124	1,406
Segment assets	140,259		140,259		$ 137,914
Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	5,215	5,150	10,530	10,090
Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	294	279	997	927
Commercial Renewables [Member]
Segment Reporting Information [Line Items]
Operating revenues	119	110	220	238
Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	5,628	5,539	11,747	11,255
Other [Member]
Segment Reporting Information [Line Items]
Operating revenues	15	16	31	29
Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment income (loss)	641	782	1,527	1,575
Segment assets	137,617		137,617
Operating Segments [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	5,223	5,158	10,546	10,105
Segment income (loss)	575	729	1,325	1,364
Segment assets	121,947		121,947
Operating Segments [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	318	301	1,045	971
Segment income (loss)	28	27	144	160
Segment assets	11,437		11,437
Operating Segments [Member] | Commercial Renewables [Member]
Segment Reporting Information [Line Items]
Operating revenues	119	110	220	238
Segment income (loss)	38	26	58	51
Segment assets	4,233		4,233
Operating Segments [Member] | Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	5,660	5,569	11,811	11,314
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues	(49)	(49)	(100)	(98)
Segment assets	181		181
Intersegment Eliminations [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	8	8	16	15
Intersegment Eliminations [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	24	22	48	44
Intersegment Eliminations [Member] | Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	32	30	64	59
Intersegment Eliminations [Member] | Other [Member]
Segment Reporting Information [Line Items]
Operating revenues	17	19	36	39
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Segment income (loss)	(136)	(94)	(402)	(171)
Segment assets	2,461		2,461
Corporate, Non-Segment [Member] | Other [Member]
Segment Reporting Information [Line Items]
Operating revenues	32	35	67	68
Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Operating revenues	459	437	983	955
Segment income (loss)	46	30	21	72
Segment assets	8,101		8,101		$ 7,875
Duke Energy Ohio [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	346	329	682	665
Duke Energy Ohio [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	103	100	277	270
Duke Energy Ohio [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	449	429	959	935
Segment income (loss)	57	39	124	88
Segment assets	8,063		8,063
Duke Energy Ohio [Member] | Operating Segments [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Segment income (loss)	39	22	72	46
Segment assets	5,336		5,336
Duke Energy Ohio [Member] | Operating Segments [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Segment income (loss)	18	17	52	42
Segment assets	2,727		2,727
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	10	8	24	20
Segment income (loss)	(11)	$ (9)	(103)	$ (16)
Segment assets	$ 40		$ 40