Changes in Accumulated Other Comprehensive Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 161,929	$ 160,242
Components of Other Comprehensive Income (Loss):
Other Comprehensive Gain (Loss), Net of Tax	(5)	57
Ending balance	161,656	160,434
Related income taxes	2,371	2,914
Total
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(2,960)	(2,798)
Components of Other Comprehensive Income (Loss):
Before Reclassifications	(37)	7
Reclassifications	32	50
Other Comprehensive Gain (Loss), Net of Tax	(5)	57
Ending balance	(2,965)	(2,741)
Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(192)	(203)
Components of Other Comprehensive Income (Loss):
Before Reclassifications	(20)	7
Reclassifications	0	0
Other Comprehensive Gain (Loss), Net of Tax	(20)	7
Ending balance	(212)	(196)
Unrealized Holding Gains (Losses) on Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(11)	(12)
Components of Other Comprehensive Income (Loss):
Before Reclassifications	(6)	(4)
Reclassifications	0	0
Other Comprehensive Gain (Loss), Net of Tax	(6)	(4)
Ending balance	(17)	(16)
Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	5	(12)
Components of Other Comprehensive Income (Loss):
Before Reclassifications	(25)	(2)
Reclassifications	(7)	15
Other Comprehensive Gain (Loss), Net of Tax	(32)	13
Ending balance	(27)	1
Defined Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(2,762)	(2,571)
Components of Other Comprehensive Income (Loss):
Before Reclassifications	14	6
Reclassifications	39	35
Other Comprehensive Gain (Loss), Net of Tax	53	41
Ending balance	(2,709)	$ (2,530)
Defined Benefit Plans | Reclassification out of Accumulated Other Comprehensive Income
Components of Other Comprehensive Income (Loss):
Employee Benefits for reclassified components	58
Related income taxes	$ 19