Retirement-Related Benefits - Cost of Pension Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Cost/(Income) of Pension Plans
Total defined benefit and contribution pension plans cost recognized in the Consolidated Income Statement	$ 6,319	$ 598	$ 7,252	$ 1,816
U.S. | Pension Plans
Cost/(Income) of Pension Plans
Interest cost	$ 282	$ 277	$ 885	$ 832
Interest cost - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Expected return on plan assets	$ (432)	$ (451)	$ (1,382)	$ (1,352)
Expected return on plan assets - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Amortization of prior service costs/(credits)	$ 2	$ 4	$ 6	$ 12
Amortization of prior service costs/(credits) - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Recognized actuarial losses	$ 132	$ 249	$ 490	$ 747
Recognized actuarial losses - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Curtailments and settlements	$ 5,894		$ 5,894
Curtailments and settlements - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Other costs/(credits) - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Total net periodic pension / nonpension (income)/cost of defined benefit plans	$ 5,877	$ 80	$ 5,893	$ 239
Cost of defined contribution plans	134	152	416	455
Total defined benefit and contribution pension plans cost recognized in the Consolidated Income Statement	6,012	232	6,309	694
U.S. | Nonpension Postretirement Plans
Cost/(Income) of Pension Plans
Service cost	1	2	4	5
Interest cost	$ 21	$ 16	$ 58	$ 49
Interest cost - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Expected return on plan assets - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Amortization of prior service costs/(credits)	$ (2)	$ 1	$ (1)	$ 3
Amortization of prior service costs/(credits) - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Recognized actuarial losses	$ 1	$ 13	$ 6	$ 39
Recognized actuarial losses - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Curtailments and settlements - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Total net periodic pension / nonpension (income)/cost of defined benefit plans	$ 21	$ 32	$ 67	$ 96
Non-US | Pension Plans
Cost/(Income) of Pension Plans
Service cost	57	67	180	201
Interest cost	$ 124	$ 106	$ 394	$ 322
Interest cost - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Expected return on plan assets	$ (246)	$ (274)	$ (778)	$ (833)
Expected return on plan assets - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Amortization of prior service costs/(credits)	$ 3	$ (2)	$ 10	$ (9)
Amortization of prior service costs/(credits) - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Recognized actuarial losses	$ 247	$ 347	$ 784	$ 1,055
Recognized actuarial losses - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Curtailments and settlements	$ 19	$ 13	$ 38	$ 46
Curtailments and settlements - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Multi-employer plans	$ 4	$ 2	$ 11	$ 13
Other costs/(credits)	$ 8	$ 7	$ 24	$ 21
Other costs/(credits) - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Total net periodic pension / nonpension (income)/cost of defined benefit plans	$ 216	$ 266	$ 663	$ 817
Cost of defined contribution plans	91	100	280	306
Total defined benefit and contribution pension plans cost recognized in the Consolidated Income Statement	307	366	943	1,122
Non-US | Nonpension Postretirement Plans
Cost/(Income) of Pension Plans
Service cost	1	1	2	3
Interest cost	$ 8	$ 8	$ 26	$ 25
Interest cost - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Expected return on plan assets	$ 0	$ (1)	$ (2)	$ (2)
Expected return on plan assets - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Amortization of prior service costs/(credits)	$ 0	$ 0	$ 0	$ 0
Amortization of prior service costs/(credits) - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Recognized actuarial losses	$ 1	$ 4	$ 3	$ 11
Recognized actuarial losses - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Curtailments and settlements				$ 0
Curtailments and settlements - income statement location	Other (income) and expense	Other (income) and expense	Other (income) and expense	Other (income) and expense
Total net periodic pension / nonpension (income)/cost of defined benefit plans	$ 10	$ 12	$ 30	$ 37