Pension and Other Benefit Plans - Changes in Accumulated Postretirement Benefit Obligation, Plan Assets and Funded Status (Detail) - Postretirement medical plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Change in Projected Benefit Obligations:
Projected benefit obligation at beginning of year	$ 805	$ 808
Service cost	19	16	$ 23
Interest cost	41	42	33
Contribution by plan participants	6	7
Actuarial losses (gains)	(37)	(7)
Benefits paid	(53)	(61)
Projected benefit obligation at end of year	781	805	808
Change in Plan Assets:
Plan assets at fair value at beginning of year	964	938
Actual return on plan assets	1	87
Contributions by plan participants	6	7
Benefits paid	(58)	(68)
Plan assets at fair value at end of year	913	964	$ 938
Asset / (Unfunded Liability)	132	159
Amounts Recognized in Accumulated Other Comprehensive Loss:
Actuarial losses	224	239
Prior service credit	13	36
Total amount recognized in accumulated other comprehensive income	$ 237	$ 275