Retirement Benefits - Schedule of Reconciliation of Benefit Obligations, Plan Assets, and Unfunded or Funded Status (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Change in benefit obligation
Settlements	$ (943)
Change in plan assets
Beginning balance at fair value		$ 24,092
Ending balance at fair value	24,608	24,608	$ 24,092
Qualified Defined  Benefit Pension Plans
Change in benefit obligation
Beginning balance		27,199	28,959
Service cost		50	60	$ 65
Interest cost		1,472	1,398	1,459
Actuarial losses (gains)		685	(1,556)
Settlements		(943)	0
Plan amendments		5	2
Benefits paid		(1,733)	(1,664)
Medicare Part D subsidy		0	0
Participants’ contributions		0	0
Ending balance	26,735	26,735	27,199	28,959
Change in plan assets
Beginning balance at fair value		22,414	22,800
Actual return on plan assets		2,252	288
Settlements		(943)	0
Benefits paid		(1,733)	(1,664)
Company contributions		860	990
Medicare Part D subsidy		0	0
Participants’ contributions		0	0
Ending balance at fair value	22,850	22,850	22,414	$ 22,800
Net (unfunded) funded status of the plans	$ (3,885)	$ (3,885)	$ (4,785)
Weighted average discount rate	5.375%	5.375%	5.625%	5.00%
Increased (decrease) in benefit obligation		$ 700	$ (1,800)
Net losses due to changes in demographic data and assumptions		$ 250
Actual return on plan assets (percent)	10.50%	10.50%
Retiree Medical and Life Insurance Plans
Change in benefit obligation
Beginning balance		$ 1,114	1,328
Service cost		3	5	$ 5
Interest cost		58	63	68
Actuarial losses (gains)		42	(158)
Settlements		0	0
Plan amendments		0	0
Benefits paid		(176)	(178)
Medicare Part D subsidy		4	2
Participants’ contributions		47	52
Ending balance	$ 1,092	1,092	1,114	1,328
Change in plan assets
Beginning balance at fair value		1,678	1,715
Actual return on plan assets		205	86
Settlements		0	0
Benefits paid		(176)	(178)
Company contributions		0	1
Medicare Part D subsidy		4	2
Participants’ contributions		47	52
Ending balance at fair value	1,758	1,758	1,678	$ 1,715
Net (unfunded) funded status of the plans	$ 666	$ 666	$ 564
Weighted average discount rate	5.25%	5.25%	5.50%	5.00%
Actual return on plan assets (percent)	10.50%	10.50%	1.00%
Long-term rate of return assumption (percent)			6.50%