Borrowings and Other Financing Instruments - Long-Term Borrowings (Details) - Series Due May 15, 2035 - Bonds $ in Millions	Sep. 30, 2025 USD ($)
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 500
Debt Instrument, Interest Rate, Stated Percentage	5.30%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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