Goodwill and Intangible Assets (Schedule of Intangible Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	$ 305	$ 300
Accumulated amortization	(56)	(54)
Total intangible assets, net	249	246
Emission allowances
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	18	18
Renewable energy certificates
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	172	168
Natural gas, coal and power contracts
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	24	24
Accumulated amortization	(21)	(20)
Renewable operating and development projects
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	89	84
Accumulated amortization	(34)	(29)
Other
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	2	6
Accumulated amortization	(1)	(5)
Duke Energy Carolinas
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	53	46
Total intangible assets, net	53	46
Duke Energy Carolinas | Emission allowances
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	0	0
Duke Energy Carolinas | Renewable energy certificates
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	53	46
Progress Energy
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	123	125
Total intangible assets, net	123	125
Progress Energy | Emission allowances
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	5	5
Progress Energy | Renewable energy certificates
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	118	120
Duke Energy Progress
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	120	122
Total intangible assets, net	120	122
Duke Energy Progress | Emission allowances
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	2	2
Duke Energy Progress | Renewable energy certificates
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	118	120
Duke Energy Florida
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	3	3
Total intangible assets, net	3	3
Duke Energy Florida | Emission allowances
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	3	3
Duke Energy Ohio
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	1	2
Total intangible assets, net	1	2
Duke Energy Ohio | Emission allowances
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	0	0
Duke Energy Ohio | Renewable energy certificates
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	1	2
Duke Energy Ohio | Other
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	0	0
Accumulated amortization	0	0
Duke Energy Indiana
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	36	36
Accumulated amortization	(21)	(20)
Total intangible assets, net	15	16
Duke Energy Indiana | Emission allowances
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	12	12
Duke Energy Indiana | Natural gas, coal and power contracts
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	24	24
Accumulated amortization	$ (21)	(20)
Piedmont
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount		3
Accumulated amortization		(3)
Piedmont | Other
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount		3
Accumulated amortization		$ (3)