Retirement Benefits Funded Status of Plan Assets (Liabilities) (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Change in plan assets
Fair value of plan assets at beginning of year	$ 31,525
Fair value of plan assets at end of year	31,006	$ 31,525
Change in projected benefit obligation
Interest cost	1,600
Benefits paid	(2,100)
Amounts Recognized on the Balance Sheet
Non-current assets	2,184	1,331
Non-current liability	(1,120)	(1,290)
Pension Benefits
Change in plan assets
Fair value of plan assets at beginning of year	30,251	28,920
Net gain on plan assets	1,358	3,104
Employer contributions	96	105
Participant contributions	6	6
Benefits paid	1,942	1,894
Other	0	10
Fair value of plan assets at end of year	29,769	30,251	$ 28,920
Change in projected benefit obligation
Projected benefit obligation at beginning of year	30,443	29,067
Service cost	239	236	367
Interest cost	1,526	1,568	1,136
Participant contributions	6	6
Actuarial (gain) loss	(1,295)	1,447
Benefits paid	1,942	1,894
Other	15	13
Projected benefit obligation at end of year	28,992	30,443	29,067
Funded status	777	(192)
Amounts Recognized on the Balance Sheet
Non-current assets	1,851	1,042
Current liability	(177)	(178)
Non-current liability	(897)	(1,056)
Medical and Life Benefits
Change in plan assets
Fair value of plan assets at beginning of year	1,274	1,226
Net gain on plan assets	61	146
Employer contributions	33	34
Participant contributions	26	27
Benefits paid	157	159
Other	0	0
Fair value of plan assets at end of year	1,237	1,274	1,226
Change in projected benefit obligation
Projected benefit obligation at beginning of year	1,246	1,264
Service cost	4	5	9
Interest cost	62	67	47
Participant contributions	26	27
Actuarial (gain) loss	(19)	42
Benefits paid	157	159
Other	(12)	0
Projected benefit obligation at end of year	1,150	1,246	$ 1,264
Funded status	87	28
Amounts Recognized on the Balance Sheet
Non-current assets	333	289
Current liability	(23)	(27)
Non-current liability	$ (223)	$ (234)