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
	Mar. 31, 2024	Mar. 31, 2023
Derivatives (net)
Balance at beginning of period	$ 15	$ 34
Purchases, sales, issuances and settlements:
Settlements	(13)	(20)
Total gains (losses) included on the Condensed Consolidated Balance Sheet	4	(2)
Balance at end of period	6	12
Duke Energy Indiana
Derivatives (net)
Balance at beginning of period	13	29
Purchases, sales, issuances and settlements:
Settlements	(11)	(19)
Total gains (losses) included on the Condensed Consolidated Balance Sheet	3	1
Balance at end of period	$ 5	$ 11