Employee Benefit Plans (AOCI and Regulatory Assets and Liabilities that have Not been Recognized as Components of Periodic Benefit (Credit) Cost) (Parenthetical) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total	[1]	$ 2,717	$ 2,200
Amount included in AOCI		1,700	1,700
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total	[1]	(73)	(369)
Amount included in AOCI		$ 14	$ (155)

[1] As of December 31, 2022, of the $2.7 billion and $(73) million related to pension benefits and other postretirement benefits, $1.7 billion and $14 million, respectively, are included in AOCI, with the remainder included in regulatory assets and liabilities. As of December 31, 2021, of the $2.2 billion and $(369) million related to pension benefits and other postretirement benefits, $1.7 billion and $(155) million, respectively, are included in AOCI, with the remainder included in regulatory assets and liabilities.