Investments in Debt and Equity Securities (Realized Gains and Losses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
FV-NI:
Realized gains	$ 34	$ 146	$ 145	$ 286
Realized losses	101	37	186	60
AFS:
Realized gains	11	16	15	34
Realized losses	42	18	65	31
Duke Energy Carolinas
FV-NI:
Realized gains	18	90	93	218
Realized losses	55	23	104	39
AFS:
Realized gains	9	12	12	25
Realized losses	21	13	37	22
Progress Energy
FV-NI:
Realized gains	16	56	52	68
Realized losses	46	14	82	21
AFS:
Realized gains	2	3	3	7
Realized losses	17	3	23	6
Duke Energy Progress
FV-NI:
Realized gains	15	55	51	67
Realized losses	45	13	80	20
AFS:
Realized gains	2	3	3	7
Realized losses	$ 15	$ 3	$ 20	$ 6