Income Taxes (Schedule of Deferred Income Taxes) (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Deferred income taxes:
Total deferred income tax assets	$ 892	$ 1,015
Total deferred income tax liabilities	2,107	1,974
Total net deferred income tax liabilities	1,215	959
Depreciation method and plant basis differences	1,164	1,139
Excess deferred income taxes	(219)	(228)
Unrecovered nuclear plant cost	479	508
DESC rate refund	(89)	(113)
Toshiba settlement	(162)	(189)
Nuclear decommissioning	(44)	(54)
Deferred state income taxes	275	226
Federal benefit of deferred state income taxes	(60)	(47)
Deferred fuel, purchased energy and gas costs	107	27
Pension benefits	51	35
Other postretirement benefits	(32)	(35)
Loss and credit carryforwards	(313)	(343)
Other	58	33
Deferred investment tax credits-regulated operations	15	16
Total deferred taxes and deferred investment tax credits	$ 1,230	$ 975