Fair Value Measurements (Reconciliation of Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Unobservable Inputs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Derivatives (net)
Balance at beginning of period	$ 15	$ 34
Purchases, sales, issuances and settlements:
Purchases	29	47
Settlements	(46)	(72)
Total gains included on the Consolidated Balance Sheet	11	6
Ending balance	9	15
Duke Energy Indiana
Derivatives (net)
Balance at beginning of period	13	29
Purchases, sales, issuances and settlements:
Purchases	27	42
Settlements	(42)	(68)
Total gains included on the Consolidated Balance Sheet	10	10
Ending balance	$ 8	$ 13