Postretirement Benefit Plans - Reconciliation of Benefit Obligations, Plan Assets, and Unfunded or Funded Status (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Jun. 26, 2022	Sep. 26, 2021
Change in plan assets
Beginning balance at fair value	$ 37,361
Ending balance at fair value	24,884	$ 37,361
Qualified Defined  Benefit Pension Plans
Change in benefit obligation
Beginning balance	43,447	51,352
Service cost	87	106	$ 101
Interest cost	1,289	1,220	1,538
Actuarial (gains) losses	(10,270)	(2,045)
Settlements	(4,309)	(4,885)
Plan amendments	186	2
Benefits paid	(1,732)	(2,303)
Medicare Part D subsidy	0	0
Participants’ contributions	0	0
Ending balance	28,698	43,447	51,352
Change in plan assets
Beginning balance at fair value	35,192	38,481
Actual return on plan assets	(5,923)	3,899
Settlements	(4,309)	(4,885)
Benefits paid	(1,732)	(2,303)
Company contributions	0	0
Medicare Part D subsidy	0	0
Participants’ contributions	0	0
Ending balance at fair value	23,228	35,192	$ 38,481
Net (unfunded) funded status of the plans	$ (5,470)	$ (8,255)
Weighted average discount rate	5.25%	2.875%	2.50%	4.75%	2.75%
Actual return on plan assets (percent)	(18.00%)
Qualified Defined  Benefit Pension Plans | Qualified Plan
Change in plan assets
Weighted average discount rate	5.25%	2.875%	2.50%
Increased (decrease) in benefit obligation	$ 10,200	$ 2,300
Changes in longevity assumptions		250
Retiree Medical and Life Insurance Plans
Change in benefit obligation
Beginning balance	1,839	2,271
Service cost	9	13	$ 13
Interest cost	49	53	70
Actuarial (gains) losses	(396)	(352)
Settlements	0	0
Plan amendments	1	0
Benefits paid	(207)	(217)
Medicare Part D subsidy	3	4
Participants’ contributions	61	67
Ending balance	1,359	1,839	2,271
Change in plan assets
Beginning balance at fair value	2,169	2,085
Actual return on plan assets	(381)	224
Settlements	0	0
Benefits paid	(207)	(217)
Company contributions	11	6
Medicare Part D subsidy	3	4
Participants’ contributions	61	67
Ending balance at fair value	1,656	2,169	$ 2,085
Net (unfunded) funded status of the plans	$ 297	$ 330
Weighted average discount rate	5.25%	2.75%	2.375%
Retiree Medical and Life Insurance Plans | Qualified Plan
Change in plan assets
Weighted average discount rate	5.25%	2.75%	2.375%
Increased (decrease) in benefit obligation	$ 335	$ 70
Changes in longevity assumptions		$ 282
Actual return on plan assets (percent)	(18.00%)	10.50%