Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Taxes [Line Items]
Foreign pretax earnings (loss)	$ 13	$ 8	$ (2)
Deferred income tax payments	$ 102
Operating loss carryforwards, expiration year	2044
Deferred tax assets recognized	$ 2	$ 3
Domestic tax credits, expiration year	2044
Open tax years		2020 2021 2022 2023 2024
RETC Projects
Income Taxes [Line Items]
Investment proportional amortization, income tax expense	$ 148	$ 26
Investment Program, Proportional Amortization Method, Elected, Income Tax Credit and Other Income Tax Benefit, after Amortization, Statement of Cash Flows [Extensible Enumeration]	Income Tax Expense (Benefit)	Income Tax Expense (Benefit)
Investment Program, Proportional Amortization Method, Elected, Income Tax Credit and Other Income Tax Benefit, after Amortization, Statement of Income or Comprehensive Income [Extensible Enumeration]	Income Tax Expense (Benefit)	Income Tax Expense (Benefit)
Investment proportional amortization, income recapture expense	$ 16	$ 1
Investment program, proportional amortization method, income tax credit	153	24
Investment program, proportional amortization method, other income tax benefit	17	2
Amortization of investment			$ 0
Investment program, commitment amount	44
State and Local Jurisdiction
Income Taxes [Line Items]
Operating loss carryforwards, amount	$ 24	$ 43