Retirement Benefits - Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Immediate Recognition of Actuarial Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]			Other income/(loss), net
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]			Other income/(loss), net
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]			Other income/(loss), net
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Other Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]			Other income/(loss), net
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Settlement and Curtailment Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]			Other income/(loss), net
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]			Other income/(loss), net
Worldwide OPEB
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Service cost	$ 6	$ 11	$ 11	$ 21
Interest cost	57	37	115	74
Expected return on assets	0	0	0	0
Amortization of prior service costs/(credits)	1	0	2	(1)
Net remeasurement (gain)/loss	0	0	0	0
Defined Benefit Plan, Other Cost (Credit)	0	(1)	0	(1)
Settlements and curtailments	0	0	0	0
Net periodic benefit cost/(income)	64	47	128	93
Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Net remeasurement (gain)/loss	89		202
Settlements and curtailments	4		46
UNITED STATES | Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Service cost	75	125	147	250
Interest cost	405	264	813	527
Expected return on assets	(480)	(643)	(966)	(1,285)
Amortization of prior service costs/(credits)	0	1	0	1
Net remeasurement (gain)/loss	81	0	194	0
Defined Benefit Plan, Other Cost (Credit)	10	7	12	11
Settlements and curtailments	3	0	45	0
Net periodic benefit cost/(income)	94	(246)	245	(496)
Foreign Plan | Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Service cost	61	107	122	218
Interest cost	242	133	479	267
Expected return on assets	(223)	(259)	(442)	(527)
Amortization of prior service costs/(credits)	5	5	10	12
Net remeasurement (gain)/loss	8	16	8	16
Defined Benefit Plan, Other Cost (Credit)	57	10	61	17
Settlements and curtailments	1	0	1	0
Net periodic benefit cost/(income)	$ 151	$ 12	$ 239	$ 3