Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Income Taxes [Line Items]
Regulatory liability due to obligation to transfer tax rate reduction expense benefit	$ 20
Effective tax rate	15.70%	19.70%
Unrecognized tax benefit that would reduce effective tax rate	$ 9		$ 9

Income taxes.

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- Definition

Regulatory liability due to obligation to transfer tax rate reduction expense benefit.

+ References

No definition available.

+ Details

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- Definition

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-12

+ Details

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- Definition

The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15A
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-15A

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