Retirement Benefits - Status (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Plan
Plan Contributions [Abstract]
Payment for Pension and Other Postretirement Benefits	$ 592
Pension and Other Postretirement Benefit Contributions Unfunded Plans	402
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	1,000
Pension And Other Postretirement Expected Benefit Contributions Unfunded Plans	400
Pension Plan | U.S. Plans
Change in Benefit Obligation
Benefit obligation at January 1	32,867	$ 44,888
Service cost	292	500	$ 526
Interest cost	1,641	1,054	928
Amendments	581	0
Separation programs/other	(18)	4
Curtailments	0	0
Settlements	(1,479)	(1,172)
Plan participant contributions	16	18
Benefits paid	(2,417)	(2,466)
Foreign exchange translation	0	0
Actuarial (gain)/loss	1,193	(9,959)
Benefit obligation at December 31	32,676	32,867	44,888
Change in Plan Assets
Fair value of plan assets at January 1	32,922	45,909
Actual return on plan assets	2,180	(9,548)
Company contributions	238	223
Plan participant contributions	16	18
Benefits paid	(2,417)	(2,466)
Settlements	(1,479)	(1,172)
Foreign exchange translation	0	0
Defined Benefit Plan Other Increase Decrease Plan Assets	(37)	(42)
Fair value of plan assets at December 31	31,423	32,922	45,909
Funded status at December 31	(1,253)	55
Amounts Recognized on the Balance Sheet
Prepaid assets	1,229	2,064
Accrued liabilities	(2,482)	(2,009)
Total	(1,253)	55
Amounts Recognized in Accumulated Other Comprehensive Loss (pre-tax)
Unamortized prior service costs/(credits)	581	0
Pension Plans in which Accumulated Benefit Obligation Exceeds Plan Assets at December 31
Accumulated benefit obligation	14,045	15,055
Fair value of plan assets	12,154	13,576
Accumulated Benefit Obligation at December 31	32,086	32,336
Pension Plans in which Projected Benefit Obligation Exceeds Plan Assets at December 31
Projected benefit obligation	14,636	15,585
Fair value of plan assets	12,154	13,576
Expected Future Benefit Payments and Amortization
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	2,715
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	2,670
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	2,635
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	2,600
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	2,575
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Year Thereafter	12,475
Pension Plan | U.S. Plans | Alternatives
Change in Plan Assets
Fair value of plan assets at January 1	6,306
Fair value of plan assets at December 31	6,102	6,306
Pension Plan | U.S. Plans | Hedge Funds
Change in Plan Assets
Fair value of plan assets at January 1	3,342
Fair value of plan assets at December 31	3,603	3,342
Pension Plan | U.S. Plans | Private Equity Funds
Change in Plan Assets
Fair value of plan assets at January 1	1,411
Fair value of plan assets at December 31	1,093	1,411
Pension Plan | Non-U.S. Plans
Change in Benefit Obligation
Benefit obligation at January 1	21,605	34,432
Service cost	245	416	557
Interest cost	965	504	420
Amendments	46	0
Separation programs/other	255	56
Curtailments	6	(2)
Settlements	(21)	(674)
Plan participant contributions	11	12
Benefits paid	(1,257)	(1,302)
Foreign exchange translation	960	(2,877)
Actuarial (gain)/loss	1,189	(8,960)
Benefit obligation at December 31	24,004	21,605	34,432
Change in Plan Assets
Fair value of plan assets at January 1	21,344	33,085
Actual return on plan assets	1,145	(7,516)
Company contributions	756	722
Plan participant contributions	11	12
Benefits paid	(1,257)	(1,302)
Settlements	(21)	(674)
Foreign exchange translation	990	(2,973)
Defined Benefit Plan Other Increase Decrease Plan Assets	(10)	(10)
Fair value of plan assets at December 31	22,958	21,344	33,085
Funded status at December 31	(1,046)	(261)
Amounts Recognized on the Balance Sheet
Prepaid assets	3,060	3,599
Accrued liabilities	(4,106)	(3,860)
Total	(1,046)	(261)
Amounts Recognized in Accumulated Other Comprehensive Loss (pre-tax)
Unamortized prior service costs/(credits)	161	130
Pension Plans in which Accumulated Benefit Obligation Exceeds Plan Assets at December 31
Accumulated benefit obligation	9,135	8,346
Fair value of plan assets	5,587	5,068
Accumulated Benefit Obligation at December 31	22,661	20,304
Pension Plans in which Projected Benefit Obligation Exceeds Plan Assets at December 31
Projected benefit obligation	9,991	8,932
Fair value of plan assets	5,885	5,068
Expected Future Benefit Payments and Amortization
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	1,430
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	1,295
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	1,310
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	1,325
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	1,330
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Year Thereafter	6,640
Pension Plan | Non-U.S. Plans | Alternatives
Change in Plan Assets
Fair value of plan assets at January 1	1,998
Fair value of plan assets at December 31	1,764	1,998
Pension Plan | Non-U.S. Plans | Hedge Funds
Change in Plan Assets
Fair value of plan assets at January 1	1,009
Fair value of plan assets at December 31	906	1,009
Pension Plan | Non-U.S. Plans | Private Equity Funds
Change in Plan Assets
Fair value of plan assets at January 1	584
Fair value of plan assets at December 31	477	584
Worldwide OPEB
Change in Benefit Obligation
Benefit obligation at January 1	4,459	6,040
Service cost	21	42	49
Interest cost	231	146	127
Amendments	32	0
Separation programs/other	0	0
Curtailments	0	0
Settlements	0	0
Plan participant contributions	0	1
Benefits paid	(359)	(363)
Foreign exchange translation	26	(92)
Actuarial (gain)/loss	286	(1,315)
Benefit obligation at December 31	4,696	4,459	6,040
Change in Plan Assets
Fair value of plan assets at January 1	0	0
Actual return on plan assets	0	0
Company contributions	0	0
Plan participant contributions - Worldwide OPEB	0	0
Benefits paid - Worldwide OPEB	0	0
Settlements	0	0
Foreign exchange translation	0	0
Defined Benefit Plan Other Increase Decrease Plan Assets	0	0
Fair value of plan assets at December 31	0	0	$ 0
Funded status at December 31	(4,696)	(4,459)
Amounts Recognized on the Balance Sheet
Prepaid assets	0	0
Accrued liabilities	(4,696)	(4,459)
Total	(4,696)	(4,459)
Amounts Recognized in Accumulated Other Comprehensive Loss (pre-tax)
Unamortized prior service costs/(credits)	55	$ 25
Expected Future Benefit Payments and Amortization
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	340
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	340
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	340
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	330
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	330
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Year Thereafter	$ 1,610