Employee Benefit Plans (Fair Values of Pension and Post Retirement Plan Assets by Asset Category) (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Pending sales of securities and advanced subscriptions	$ 633	$ 298
Net accrued income	21	24
Pending purchases of securities	16	54
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Pending sales of securities and advanced subscriptions	19	17
Net accrued income	2	2
Pending purchases of securities	$ 2	$ 2