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, 2017	Dec. 31, 2016	Oct. 31, 2016	Dec. 31, 2015	Oct. 31, 2015
Operating Leased Assets
Rental expense on operating leases		$ 241	$ 242		$ 313
Operating Leases, Future Minimum Payments Due [Abstract]
2018		233
2019		203
2020		183
2021		150
2022		135
Thereafter		882
Total future minimum lease payments		1,786
Capital Leases, Future Minimum Payments Due [Abstract]
2018		168
2019		169
2020		174
2021		176
2022		169
Thereafter		745
Minimum annual payments		1,601
Less amount representing interest		(601)
Total		1,000
Duke Energy Carolinas [Member]
Operating Leased Assets
Rental expense on operating leases		44	45		41
Operating Leases, Future Minimum Payments Due [Abstract]
2018		36
2019		29
2020		25
2021		19
2022		16
Thereafter		52
Total future minimum lease payments		177
Capital Leases, Future Minimum Payments Due [Abstract]
2018		13
2019		13
2020		13
2021		8
2022		8
Thereafter		109
Minimum annual payments		164
Less amount representing interest		(103)
Total		61
Progress Energy [Member]
Operating Leased Assets
Rental expense on operating leases		130	140		230
Operating Leases, Future Minimum Payments Due [Abstract]
2018		133
2019		126
2020		117
2021		97
2022		90
Thereafter		525
Total future minimum lease payments		1,088
Capital Leases, Future Minimum Payments Due [Abstract]
2018		46
2019		45
2020		47
2021		45
2022		45
Thereafter		323
Minimum annual payments		551
Less amount representing interest		(283)
Total		268
Duke Energy Progress [Member]
Operating Leased Assets
Rental expense on operating leases		75	68		149
Operating Leases, Future Minimum Payments Due [Abstract]
2018		77
2019		72
2020		62
2021		48
2022		42
Thereafter		344
Total future minimum lease payments		645
Capital Leases, Future Minimum Payments Due [Abstract]
2018		21
2019		20
2020		21
2021		22
2022		21
Thereafter		227
Minimum annual payments		332
Less amount representing interest		(192)
Total		140
Duke Energy Florida [Member]
Operating Leased Assets
Rental expense on operating leases		55	72		81
Operating Leases, Future Minimum Payments Due [Abstract]
2018		56
2019		54
2020		55
2021		49
2022		48
Thereafter		181
Total future minimum lease payments		443
Capital Leases, Future Minimum Payments Due [Abstract]
2018		25
2019		25
2020		26
2021		25
2022		24
Thereafter		95
Minimum annual payments		220
Less amount representing interest		(91)
Total		129
Duke Energy Ohio [Member]
Operating Leased Assets
Rental expense on operating leases		15	16		13
Operating Leases, Future Minimum Payments Due [Abstract]
2018		20
2019		12
2020		10
2021		7
2022		4
Thereafter		5
Total future minimum lease payments		58
Capital Leases, Future Minimum Payments Due [Abstract]
2018		3
2019		1
2020		0
Minimum annual payments		4
Total		4
Duke Energy Indiana [Member]
Operating Leased Assets
Rental expense on operating leases		23	$ 23		$ 20
Operating Leases, Future Minimum Payments Due [Abstract]
2018		22
2019		14
2020		10
2021		8
2022		5
Thereafter		7
Total future minimum lease payments		66
Capital Leases, Future Minimum Payments Due [Abstract]
2018		2
2019		1
2020		1
2021		1
2022		1
Thereafter		38
Minimum annual payments		44
Less amount representing interest		(33)
Total		11
Piedmont Natural Gas [Member]
Operating Leased Assets
Rental expense on operating leases	$ 1	7		$ 5		$ 5
Operating Leases, Future Minimum Payments Due [Abstract]
2018		6
2019		5
2020		5
2021		6
2022		6
Thereafter		16
Total future minimum lease payments		$ 44