Retirement Benefits Funded Status of Plan Assets (Liabilities) (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Change in plan assets
Fair value of plan assets at beginning of year	$ 35,967
Fair value of plan assets at end of year	37,824	$ 35,967
Amounts Recognized on the Balance Sheet
Non-current liability	(3,269)	(6,498)
Pension Benefits
Change in plan assets
Fair value of plan assets at beginning of year	34,452	30,646
Net gain on plan assets	3,637	4,802
Employer contributions	104	851
Participant contributions	8	8
Benefits paid	(1,964)	(1,865)
Other	(1)	10
Fair value of plan assets at end of year	36,236	34,452	$ 30,646
Change in projected benefit obligation
Projected benefit obligation at beginning of year	40,182	36,914
Service cost	414	409	367
Interest cost	1,054	1,226	1,360
Participant contributions	8	8
Actuarial (gain) loss	(794)	3,455
Benefits paid	(1,964)	(1,865)
Other	(12)	35
Projected benefit obligation at end of year	38,888	40,182	36,914
Funded status	(2,652)	(5,730)
Amounts Recognized on the Balance Sheet
Non-current assets	462	211
Current liability	(182)	(180)
Non-current liability	(2,932)	(5,761)
Medical and Life Benefits
Change in plan assets
Fair value of plan assets at beginning of year	1,515	1,392
Net gain on plan assets	170	218
Employer contributions	37	36
Participant contributions	23	24
Benefits paid	(157)	(155)
Other	0	0
Fair value of plan assets at end of year	1,588	1,515	1,392
Change in projected benefit obligation
Projected benefit obligation at beginning of year	2,119	2,048
Service cost	16	17	16
Interest cost	53	67	80
Participant contributions	23	24
Actuarial (gain) loss	(369)	115
Benefits paid	(157)	(155)
Other	0	3
Projected benefit obligation at end of year	1,685	2,119	$ 2,048
Funded status	(97)	(604)
Amounts Recognized on the Balance Sheet
Non-current assets	285	179
Current liability	(45)	(46)
Non-current liability	$ (337)	$ (737)