Income Taxes - Schedule of Income Tax Expense (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Current income taxes, Federal	$ (13)	$ 48	$ 35
Current income taxes, State	(3)	4	(7)
Deferred income taxes, Federal	105	24	32
Deferred income taxes, State	38	13	29
Investment tax credits amortization	(6)	(9)	(7)
Total income tax expense	$ 121	$ 80	$ 82