Postretirement Plans - Schedule of Changes in the Benefit Obligation, Plan Assets and Funded Status of Pensions and OPB (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Nov. 30, 2020	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Company contribution	$ 3,000
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract]
Accrued pension plan liability, net		$ (6,516)	$ (6,141)
Pension
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning balance		55,117	75,635
Service cost		2	3	$ 3
Interest cost		2,820	2,080	1,988
Amendments			1
Actuarial loss/(gain)		1,217	(17,605)
Gross benefits paid		(4,837)	(4,971)
Subsidies
Exchange rate adjustment		6	(26)
Ending balance		54,325	55,117	75,635
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Beginning balance at fair value		49,825	67,813
Actual return on plan assets		3,756	(13,141)
Company contribution			2
Plan participants' contributions
Benefits paid		(4,698)	(4,824)
Exchange rate adjustment		8	(25)
Ending balance at fair value		48,891	49,825	67,813
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract]
Other assets		1,219	987
Accrued liabilities		(137)	(138)
Accrued retiree health care
Accrued pension plan liability, net		(6,516)	(6,141)
Net amount recognized		(5,434)	(5,292)
Other Postretirement Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning balance		2,978	4,092
Service cost		49	72	87
Interest cost		148	98	97
Amendments
Actuarial loss/(gain)		(152)	(914)
Gross benefits paid		(375)	(406)
Subsidies		2	39
Exchange rate adjustment		1	(3)
Ending balance		2,651	2,978	4,092
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Beginning balance at fair value		140	172
Actual return on plan assets		23	(27)
Company contribution
Plan participants' contributions		4	6
Benefits paid		(4)	(11)
Exchange rate adjustment
Ending balance at fair value		163	140	$ 172
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract]
Other assets		81	21
Accrued liabilities		(336)	(356)
Accrued retiree health care		(2,233)	(2,503)
Accrued pension plan liability, net
Net amount recognized		$ (2,488)	$ (2,838)