Income Taxes (Details of Income Tax Expense for Continuing Operations Including Noncontrolling Interests) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current:
Federal	$ 91	$ (69)	$ (52)
State	(70)	(3)	(39)
Total current expense (benefit)	21	(72)	(91)
Deferred:
Taxes before operating loss carryforwards and investment tax credits	(72)	135	61
Tax utilization expense (benefit) of operating loss carryforwards	43	33	34
State	95	36	7
Total deferred expense	66	204	102
Investment tax credits	(2)	(1)	(2)
Total income tax expense	$ 85	$ 131	$ 9