Borrowings and Other Financing Instruments - Money Pool (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Sep. 30, 2025	Dec. 31, 2024
Short-term Debt [Line Items]
Short-term debt	$ 0	$ 145
Money Pool
Short-term Debt [Line Items]
Borrowing limit	100	100
Short-term debt	0	7
Average amount outstanding	0	24
Maximum amount outstanding	0	$ 100
Weighted average interest rate, computed on a daily basis		5.29%
Weighted average interest rate at period end		4.58%
Commercial Paper
Short-term Debt [Line Items]
Borrowing limit	600	$ 500
Short-term debt	0	145
Average amount outstanding	0	35
Maximum amount outstanding	$ 0	$ 160
Weighted average interest rate, computed on a daily basis		5.47%
Weighted average interest rate at period end		4.66%

The effective interest rate during the reporting period.

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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- Definition

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
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- Definition

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.

+ References

No definition available.

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- Definition

Weighted average interest rate of short-term debt outstanding calculated at point in time.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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- Definition

For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, average borrowings during the period.

+ References

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- Definition

For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, the maximum amount borrowed at any time during the period.

+ References

No definition available.

+ Details

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