Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
AOCI Attributable to Parent, Net of Tax
Beginning balance	$ 1,534	$ 15,358	$ 13,687
Changes in value (net of tax effect)	1,593	(1,252)	(415)
Changes in value, tax effect	484	(384)	(133)
Reclassification into earnings (net of tax effect)	315	203	251
Reclassifications into earnings, tax effect	96	169	76
Ending balance	3,887	1,534	15,358
Deferred income tax expense in AOCI that will not be recognized until obligation is fully extinguished	760	760	760
Tax benefit	(118)	3,202	(1,431)
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax
Beginning balance	(9,038)	(7,989)	(7,825)
Beginning balance, tax effect	(1,764)	(1,549)	(1,492)
Ending balance	(7,130)	(9,038)	(7,989)
Ending balance, tax effect	(1,184)	(1,764)	(1,549)
Pension and Other Benefits Liabilities
AOCI Attributable to Parent, Net of Tax
Beginning balance	(9,078)	(8,095)	(7,925)
Changes in value (net of tax effect)	1,593	(1,269)	(422)
Reclassification into earnings (net of tax effect)	315	286	252
Ending balance	(7,170)	(9,078)	(8,095)
Other
AOCI Attributable to Parent, Net of Tax
Beginning balance	40	106	100
Changes in value (net of tax effect)	0	17	7
Reclassification into earnings (net of tax effect)	0	(83)	(1)
Ending balance	$ 40	40	$ 106
Other | Reclassification out of AOCI
AOCI Attributable to Parent, Net of Tax
Tax benefit		$ 83