Fair Value Measurements (Reconciliation of Assets and Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Derivatives (net)
Balance at beginning of period	$ 41	$ 89	$ 34	$ 24
Purchases, sales, issuances and settlements:
Purchases	3		50	77
Settlements	(18)	(21)	(76)	(13)
Total gains (losses) included on the Condensed Consolidated Balance Sheet	4	(8)	22	(28)
Balance at end of period	30	60	30	60
Duke Energy Indiana
Derivatives (net)
Balance at beginning of period	37	84	29	22
Purchases, sales, issuances and settlements:
Purchases			42	74
Settlements	(14)	(20)	(70)	(10)
Total gains (losses) included on the Condensed Consolidated Balance Sheet	4	(8)	26	(30)
Balance at end of period	$ 27	$ 56	$ 27	$ 56