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, 2023	Dec. 31, 2022	Dec. 31, 2021
Change in Projected Benefit Obligations:
Projected benefit obligation at beginning of year	$ 808	$ 1,146
Service cost	16	23	$ 28
Interest cost	42	33	32
Contribution by plan participants	7	9
Actuarial losses (gains)	(7)	(338)
Benefits paid	(61)	(65)
Projected benefit obligation at end of year	805	808	1,146
Change in Plan Assets:
Plan assets at fair value at beginning of year	938	1,318
Actual return on plan assets	87	(323)
Contributions by plan participants	7	8
Benefits paid	(68)	(65)
Plan assets at fair value at end of year	964	938	$ 1,318
Asset	159	130
Amounts Recognized in Accumulated Other Comprehensive Loss:
Actuarial losses	239	199
Prior service credit	36	59
Total amount recognized in accumulated other comprehensive income	$ 275	$ 258