Retirement-Related Benefits - Cost of Pension Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cost/(Income) of Pension Plans
Total defined benefit and contribution pension plans cost recognized in the Consolidated Income Statement	$ 281	$ 478
U.S. | Pension Plans
Cost/(Income) of Pension Plans
Interest cost	$ 272	$ 302
Interest cost - income statement location	Other (income) and expense	Other (income) and expense
Expected return on plan assets	$ (382)	$ (475)
Expected return on plan assets - income statement location	Other (income) and expense	Other (income) and expense
Amortization of prior service costs/(credits)		$ 2
Amortization of prior service costs/(credits) - income statement location	Other (income) and expense	Other (income) and expense
Recognized actuarial losses	$ 27	$ 179
Recognized actuarial losses - income statement location	Other (income) and expense	Other (income) and expense
Curtailments and settlements - income statement location	Other (income) and expense	Other (income) and expense
Other costs/(credits) - income statement location	Other (income) and expense	Other (income) and expense
Total net periodic pension / nonpension (income)/cost of defined benefit plans	$ (82)	$ 8
Cost of defined contribution plans	172	141
Total defined benefit and contribution pension plans cost recognized in the Consolidated Income Statement	90	149
U.S. | Nonpension Postretirement Plans
Cost/(Income) of Pension Plans
Service cost	1	1
Interest cost	$ 29	$ 18
Interest cost - income statement location	Other (income) and expense	Other (income) and expense
Expected return on plan assets - income statement location	Other (income) and expense	Other (income) and expense
Amortization of prior service costs/(credits)	$ (7)	$ 1
Amortization of prior service costs/(credits) - income statement location	Other (income) and expense	Other (income) and expense
Recognized actuarial losses		$ 2
Recognized actuarial losses - income statement location	Other (income) and expense	Other (income) and expense
Curtailments and settlements - income statement location	Other (income) and expense	Other (income) and expense
Total net periodic pension / nonpension (income)/cost of defined benefit plans	$ 23	$ 23
Non-US | Pension Plans
Cost/(Income) of Pension Plans
Service cost	44	64
Interest cost	$ 288	$ 139
Interest cost - income statement location	Other (income) and expense	Other (income) and expense
Expected return on plan assets	$ (356)	$ (274)
Expected return on plan assets - income statement location	Other (income) and expense	Other (income) and expense
Amortization of prior service costs/(credits)	$ 5	$ 4
Amortization of prior service costs/(credits) - income statement location	Other (income) and expense	Other (income) and expense
Recognized actuarial losses	$ 102	$ 278
Recognized actuarial losses - income statement location	Other (income) and expense	Other (income) and expense
Curtailments and settlements	$ (1)	$ 8
Curtailments and settlements - income statement location	Other (income) and expense	Other (income) and expense
Multi-employer plans	$ 4	$ 4
Other costs/(credits)	$ 9	$ 9
Other costs/(credits) - income statement location	Other (income) and expense	Other (income) and expense
Total net periodic pension / nonpension (income)/cost of defined benefit plans	$ 95	$ 231
Cost of defined contribution plans	97	98
Total defined benefit and contribution pension plans cost recognized in the Consolidated Income Statement	192	328
Non-US | Nonpension Postretirement Plans
Cost/(Income) of Pension Plans
Service cost	1	1
Interest cost	$ 9	$ 9
Interest cost - income statement location	Other (income) and expense	Other (income) and expense
Expected return on plan assets	$ (1)	$ 0
Expected return on plan assets - income statement location	Other (income) and expense	Other (income) and expense
Amortization of prior service costs/(credits)	$ 0	$ 0
Amortization of prior service costs/(credits) - income statement location	Other (income) and expense	Other (income) and expense
Recognized actuarial losses	$ 0	$ 1
Recognized actuarial losses - income statement location	Other (income) and expense	Other (income) and expense
Curtailments and settlements - income statement location	Other (income) and expense	Other (income) and expense
Total net periodic pension / nonpension (income)/cost of defined benefit plans	$ 9	$ 10