Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Detail)	6 Months Ended
Jun. 30, 2025	Jun. 30, 2024
Income Tax Disclosure [Abstract]
U.S. statutory rate	21.00%	21.00%
Increases (reductions) resulting from:
State taxes, net of federal benefit	7.70%	4.00%
Reversal of excess deferred income taxes	(2.70%)	(5.70%)
Allowance for equity funds used during construction	0.00%	(0.70%)
Remeasurements and settlements of uncertain tax positions	(9.70%)
Other, net	0.10%	0.10%
Effective tax rate	16.40%	18.70%

Effective income tax rate reconciliation allowance for equity funds used during construction.

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- Definition

Effective income tax reconciliation reversal of excess deferred income taxes.

+ References

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- Definition

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

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- Definition

Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to income tax settlements. Including, but not limited to, domestic tax settlement, foreign tax settlement, state and local tax settlement, and other tax settlements.

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