Post-Employment Benefits - Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost — benefits earned during the year	$ 230	$ 374	$ 391
Interest cost on projected benefit obligations	455	300	248
Expected return on plans’ assets	(971)	(931)	(843)
Amortization of actuarial losses (gains)	11	231	317
Amortization of prior service costs (credits)	1	1	1
Total net cost (income)	(274)	(25)	114
Medical and Dental Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost — benefits earned during the year	38	50	56
Interest cost on projected benefit obligations	59	36	33
Expected return on plans’ assets	(23)	(30)	(27)
Amortization of actuarial losses (gains)	(2)	11	29
Amortization of prior service costs (credits)	(13)	(24)	(28)
Total net cost (income)	$ 59	$ 43	$ 63