Borrowings and Other Financing Instruments - Letters of Credit (Details) - USD ($) $ in Millions |
6 Months Ended | |
|---|---|---|
Jun. 30, 2025 |
Dec. 31, 2024 |
|
| Line of Credit Facility [Abstract] | ||
| Term of letters of credit (in years) | 1 year | |
| Short-term debt | $ 0 | $ 85 |
| Line of Credit Facility [Line Items] | ||
| Term of letters of credit (in years) | 1 year | |
| Short-term debt | $ 0 | 85 |
| Letter of Credit | ||
| Line of Credit Facility [Abstract] | ||
| Short-term debt | 30 | 31 |
| Line of Credit Facility [Line Items] | ||
| Short-term debt | $ 30 | $ 31 |
| Letter of Credit | Letter of Credit | ||
| Line of Credit Facility [Abstract] | ||
| Term of letters of credit (in years) | 1 year | |
| Line of Credit Facility [Line Items] | ||
| Term of letters of credit (in years) | 1 year |