Pension Plans and Other Postretirement Benefit Plans - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Defined Benefit Plan Disclosure [Line Items]
Payment for pension benefits	$ 3	$ 3
Percentage of service related net periodic benefit costs capitalized to utility property	45.00%
Percentage of service related net periodic benefit costs recorded to operating expenses	55.00%
Percentage of non-service related net periodic benefit costs capitalized to regulatory assets	45.00%
Percentage of non-service related net periodic benefit costs recorded to other expense	55.00%
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contributions to pension plan	$ 10

Percentage of non-service related net periodic benefit costs capitalized to regulatory assets.

No definition available.

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- Definition

Percentage of non-service related net periodic benefit costs recorded to other expense.

+ References

No definition available.

+ Details

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- Definition

Percentage of service related net periodic benefit costs capitalized to utility property.

+ References

No definition available.

+ Details

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- Definition

Percentage of service related net periodic benefit costs recorded to operating expenses.

+ References

No definition available.

+ Details

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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.

+ Details

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- Definition

Amount of contribution expected to be received by defined benefit plan from employer in next fiscal year following current fiscal year.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 18
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480482/715-20-55-18

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

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- Definition

Amount of cash outflow for pension benefit. Includes, but is not limited to, employer contribution to fund plan asset and payment to retiree. Excludes other postretirement benefit.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 25
-Subparagraph (g)
-SubTopic 10
-Topic 230
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-25

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- Details

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