Commitments and Contingencies (Future Minimum Payments for Operating and Capital Leases) (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Operating Leased Assets
Rental expense on operating leases		$ 268	$ 241	$ 242
Operating Leases, Future Minimum Payments Due [Abstract]
2019		239
2020		219
2021		186
2022		170
2023		160
Thereafter		1,017
Total future minimum lease payments		1,991
Capital Leases, Future Minimum Payments Due [Abstract]
2019		170
2020		174
2021		177
2022		165
2023		165
Thereafter		577
Minimum annual payments		1,428
Less amount representing interest		(487)
Total		941
Duke Energy Carolinas [Member]
Operating Leased Assets
Rental expense on operating leases		49	44	45
Operating Leases, Future Minimum Payments Due [Abstract]
2019		33
2020		29
2021		19
2022		19
2023		17
Thereafter		68
Total future minimum lease payments		185
Capital Leases, Future Minimum Payments Due [Abstract]
2019		20
2020		20
2021		15
2022		15
2023		15
Thereafter		204
Minimum annual payments		289
Less amount representing interest		(180)
Total		109
Progress Energy [Member]
Operating Leased Assets
Rental expense on operating leases		143	130	140
Operating Leases, Future Minimum Payments Due [Abstract]
2019		97
2020		90
2021		79
2022		76
2023		77
Thereafter		455
Total future minimum lease payments		874
Capital Leases, Future Minimum Payments Due [Abstract]
2019		45
2020		46
2021		45
2022		45
2023		45
Thereafter		230
Minimum annual payments		456
Less amount representing interest		(205)
Total		251
Duke Energy Progress [Member]
Operating Leased Assets
Rental expense on operating leases		75	75	68
Operating Leases, Future Minimum Payments Due [Abstract]
2019		49
2020		46
2021		37
2022		34
2023		35
Thereafter		314
Total future minimum lease payments		515
Capital Leases, Future Minimum Payments Due [Abstract]
2019		20
2020		21
2021		20
2022		21
2023		21
Thereafter		209
Minimum annual payments		312
Less amount representing interest		(175)
Total		137
Duke Energy Florida [Member]
Operating Leased Assets
Rental expense on operating leases		68	55	72
Operating Leases, Future Minimum Payments Due [Abstract]
2019		48
2020		44
2021		42
2022		42
2023		42
Thereafter		141
Total future minimum lease payments		359
Capital Leases, Future Minimum Payments Due [Abstract]
2019		25
2020		25
2021		25
2022		24
2023		24
Thereafter		21
Minimum annual payments		144
Less amount representing interest		(30)
Total		114
Duke Energy Ohio [Member]
Operating Leased Assets
Rental expense on operating leases		13	15	16
Operating Leases, Future Minimum Payments Due [Abstract]
2019		2
2020		2
2021		2
2022		2
2023		2
Thereafter		23
Total future minimum lease payments		33
Capital Leases, Future Minimum Payments Due [Abstract]
2019		2
Minimum annual payments		2
Total		2
Duke Energy Indiana [Member]
Operating Leased Assets
Rental expense on operating leases		21	23	$ 23
Operating Leases, Future Minimum Payments Due [Abstract]
2019		6
2020		5
2021		4
2022		4
2023		5
Thereafter		66
Total future minimum lease payments		90
Capital Leases, Future Minimum Payments Due [Abstract]
2019		1
2020		1
2021		1
2022		1
2023		1
Thereafter		27
Minimum annual payments		32
Less amount representing interest		(22)
Total		10
Piedmont Natural Gas [Member]
Operating Leased Assets
Rental expense on operating leases	$ 1	11	$ 7		$ 5
Operating Leases, Future Minimum Payments Due [Abstract]
2019		5
2020		5
2021		5
2022		5
2023		6
Thereafter		11
Total future minimum lease payments		$ 37