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, 2022	Dec. 31, 2021	Dec. 31, 2020
Change in Projected Benefit Obligations:
Projected benefit obligation at beginning of year	$ 1,146	$ 1,234
Service cost	23	28	$ 31
Interest cost	33	32	36
Contribution by plan participants	9	10
Actuarial gains	(338)	(95)
Benefits paid	(65)	(63)
Projected benefit obligation at end of year	808	1,146	1,234
Change in Plan Assets:
Plan assets at fair value at beginning of year	1,318	1,356
Actual return on plan assets	(323)	15
Contributions by plan participants	8	10
Benefits paid	(65)	(63)
Plan assets at fair value at end of year	938	1,318	$ 1,356
Asset	130	172
Amounts Recognized in Accumulated Other Comprehensive Loss:
Actuarial losses	199	225
Prior service credit	59	81
Total amount recognized in accumulated other comprehensive income	$ 258	$ 306