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, 2026 |
Mar. 31, 2025 |
|
| Derivatives (net) | ||
| Balance at beginning of period | $ 9 | $ 9 |
| Purchases, sales, issuances and settlements: | ||
| Settlements | (4) | (6) |
| Total losses included on the Condensed Consolidated Balance Sheet | (1) | 0 |
| Balance at end of period | 4 | 3 |
| Duke Energy Indiana | ||
| Derivatives (net) | ||
| Balance at beginning of period | 9 | 8 |
| Purchases, sales, issuances and settlements: | ||
| Settlements | (3) | (6) |
| Total losses included on the Condensed Consolidated Balance Sheet | (2) | |
| Balance at end of period | $ 4 | $ 2 |