Changes in Accumulated Other Comprehensive Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 139,940	$ 132,726
Components of Other Comprehensive Income (Loss):
Before Reclassifications	108	693
Reclassifications	129	333
Other Comprehensive Gain (Loss), Net of Tax	237	1,026
Ending balance	147,100	132,933
Related income taxes	2,777	779
Total
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(3,889)	(5,612)
Components of Other Comprehensive Income (Loss):
Other Comprehensive Gain (Loss), Net of Tax	237	1,026
Ending balance	(3,652)	(4,586)
Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(162)	(107)
Components of Other Comprehensive Income (Loss):
Before Reclassifications	(11)	(19)
Reclassifications	0	0
Other Comprehensive Gain (Loss), Net of Tax	(11)	(19)
Ending balance	(173)	(126)
Unrealized Holding Gains (Losses) on Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(11)	(10)
Components of Other Comprehensive Income (Loss):
Before Reclassifications	0	(3)
Reclassifications	0	0
Other Comprehensive Gain (Loss), Net of Tax	0	(3)
Ending balance	(11)	(13)
Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	0	0
Components of Other Comprehensive Income (Loss):
Before Reclassifications	2	0
Reclassifications	0	0
Other Comprehensive Gain (Loss), Net of Tax	2	0
Ending balance	2	0
Defined Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(3,716)	(5,495)
Components of Other Comprehensive Income (Loss):
Before Reclassifications	117	715
Reclassifications	129	333
Other Comprehensive Gain (Loss), Net of Tax	246	1,048
Ending balance	(3,470)	$ (4,447)
Defined Benefit Plans | Reclassification out of Accumulated Other Comprehensive Income
Components of Other Comprehensive Income (Loss):
Employee Benefits for reclassified components	154
Related income taxes	$ 25