Investments in Debt and Equity Securities (Realized Gains and Losses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
FV-NI:
Realized gains	$ 724	$ 366	$ 172
Realized losses	141	174	151
AFS:
Realized gains	56	96	94
Realized losses	54	51	67
Duke Energy Carolinas
FV-NI:
Realized gains	440	64	113
Realized losses	96	99	107
AFS:
Realized gains	38	60	55
Realized losses	37	37	38
Progress Energy
FV-NI:
Realized gains	284	302	59
Realized losses	45	75	44
AFS:
Realized gains	16	24	36
Realized losses	14	13	29
Duke Energy Progress
FV-NI:
Realized gains	283	52	38
Realized losses	44	59	33
AFS:
Realized gains	15	24	7
Realized losses	13	13	5
Duke Energy Florida
FV-NI:
Realized gains	1	250	21
Realized losses	1	$ 16	11
AFS:
Realized gains	1		29
Realized losses	$ 1		$ 24