Investments in Debt and Equity Securities (Realized Gains and Losses) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
FV-NI:
Realized gains	$ 61	$ 25	$ 107	$ 170
Realized losses	35	61	117	247
AFS:
Realized gains	16	7	37	22
Realized losses	45	40	104	105
Duke Energy Carolinas
FV-NI:
Realized gains	43	16	70	109
Realized losses	17	39	64	143
AFS:
Realized gains	12	7	21	19
Realized losses	26	20	54	57
Progress Energy
FV-NI:
Realized gains	18	9	37	61
Realized losses	18	22	53	104
AFS:
Realized gains	4		16	3
Realized losses	19	9	50	32
Duke Energy Progress
FV-NI:
Realized gains	15	9	34	60
Realized losses	18	21	52	101
AFS:
Realized gains	4		15	3
Realized losses	$ 18	$ 9	$ 47	$ 29