Goodwill and Intangible Assets (Schedule of Intangible Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Asset Impairment Charges	$ 282	$ 18	$ 106
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	276	271
Accumulated amortization	(46)	(45)
Total intangible assets, net	230	226
Amortization expense	7	6	5
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
2017	3
2018	2
2019	2
2020	2
2021	2
Wind Project [Member]
Finite-Lived Intangible Assets [Line Items]
Asset Impairment Charges	69
Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	19	19
Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	148	125
Gas Coal And Power Contracts [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	24	24
Accumulated amortization	(19)	(17)
Renewable Operating and Development Projects [Member]
Finite-Lived Intangible Assets [Line Items]
Asset Impairment Charges	69
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	79	97
Accumulated amortization	(22)	(23)
Renewable Operating and Development Projects [Member] | Property, Plant and Equipment [Member]
Finite-Lived Intangible Assets [Line Items]
Asset Impairment Charges	58
Renewable Operating and Development Projects [Member] | Finite-Lived Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Asset Impairment Charges	11
Renewable Operating and Development Projects [Member] | Wind Project [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount		18
Accumulated amortization		(7)
Other Intangible Assets [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	6	6
Accumulated amortization	(5)	(5)
Duke Energy Carolinas [Member]
Finite-Lived Intangible Assets [Line Items]
Asset Impairment Charges		1	1
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	39	37
Total intangible assets, net	39	37
Duke Energy Carolinas [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	1	1
Duke Energy Carolinas [Member] | Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	38	36
Progress Energy [Member]
Finite-Lived Intangible Assets [Line Items]
Asset Impairment Charges	156	7	12
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	112	90
Total intangible assets, net	112	90
Progress Energy [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	5	6
Progress Energy [Member] | Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	107	84
Duke Energy Progress [Member]
Finite-Lived Intangible Assets [Line Items]
Asset Impairment Charges	19	1	5
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	109	86
Total intangible assets, net	109	86
Duke Energy Progress [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	2	2
Duke Energy Progress [Member] | Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	107	84
Duke Energy Florida [Member]
Finite-Lived Intangible Assets [Line Items]
Asset Impairment Charges	138	6	7
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	3	4
Total intangible assets, net	3	4
Duke Energy Florida [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	3	4
Duke Energy Ohio [Member]
Finite-Lived Intangible Assets [Line Items]
Asset Impairment Charges	1
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	3	4
Total intangible assets, net	3	4
Duke Energy Ohio [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	0
Duke Energy Ohio [Member] | Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	3	4
Duke Energy Ohio [Member] | Other Intangible Assets [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	0
Accumulated amortization	0
Duke Energy Indiana [Member]
Finite-Lived Intangible Assets [Line Items]
Asset Impairment Charges	18	8	88
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	37	37
Accumulated amortization	(19)	(17)
Total intangible assets, net	18	20
Amortization expense	1	1	$ 1
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
2017	1
2018	0
2019	0
2020	0
2021	0
Duke Energy Indiana [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	13	13
Duke Energy Indiana [Member] | Gas Coal And Power Contracts [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	24	24
Accumulated amortization	(19)	(17)
Piedmont Natural Gas [Member]
Finite-Lived Intangible Assets [Line Items]
Asset Impairment Charges	7
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	3	3
Accumulated amortization	(3)	(3)
Piedmont Natural Gas [Member] | Other Intangible Assets [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	3	3
Accumulated amortization	$ (3)	$ (3)