Post-Employment Benefits - Summary of Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Plan Assets at Fair Value
Plan assets at fair value, January 1	$ 11,675
Plan assets at fair value, December 31	13,373	$ 11,675
Long-term liabilities	(1,964)	(1,784)
Defined Benefit Plans
Projected Benefit Obligations
Projected benefit obligations, January 1	9,167	12,773
Service cost — benefits earned during the year	230	374	$ 391
Interest cost on projected benefit obligations	455	300	248
(Gains) losses, primarily changes in discount rates, plan design changes, law changes and differences between actual and estimated health care costs	458	(3,645)
Benefits paid	(377)	(368)
Other, including foreign currency translation	97	(267)
Projected benefit obligations, December 31	10,030	9,167	12,773
Plan Assets at Fair Value
Plan assets at fair value, January 1	11,373	13,468
Actual return (loss) on plan assets	1,611	(1,856)
Company contributions	349	413
Benefits paid	(377)	(368)
Other, including foreign currency translation	129	(284)
Plan assets at fair value, December 31	13,085	11,373	13,468
Projected benefit obligations less (greater) than plan assets, December 31	3,055	2,206
Long-term assets	4,164	3,200
Short-term liabilities	(36)	(32)
Long-term liabilities	(1,073)	(962)
Net asset (liability)	3,055	2,206
Amounts Recognized in Accumulated Other Comprehensive Income (loss):
Actuarial losses, net	1,751	1,960
Prior service costs (credits)	6	(6)
Total	1,757	1,954
Medical and Dental Plans
Projected Benefit Obligations
Projected benefit obligations, January 1	1,126	1,566
Service cost — benefits earned during the year	38	50	56
Interest cost on projected benefit obligations	59	36	33
(Gains) losses, primarily changes in discount rates, plan design changes, law changes and differences between actual and estimated health care costs	35	(437)
Benefits paid	(77)	(70)
Other, including foreign currency translation	0	(19)
Projected benefit obligations, December 31	1,181	1,126	1,566
Plan Assets at Fair Value
Plan assets at fair value, January 1	302	370
Actual return (loss) on plan assets	26	(33)
Company contributions	37	35
Benefits paid	(77)	(70)
Other, including foreign currency translation	0	0
Plan assets at fair value, December 31	288	302	$ 370
Projected benefit obligations less (greater) than plan assets, December 31	(893)	(824)
Long-term assets	0	0
Short-term liabilities	(2)	(2)
Long-term liabilities	(891)	(822)
Net asset (liability)	(893)	(824)
Amounts Recognized in Accumulated Other Comprehensive Income (loss):
Actuarial losses, net	62	27
Prior service costs (credits)	(22)	(33)
Total	$ 40	$ (6)