Retirement Benefits - Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
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	$ 6	$ 12	$ 11
Interest cost	56	57	113	115
Expected return on assets	0	0	0	0
Amortization of prior service costs/(credits)	3	1	5	2
Net remeasurement (gain)/loss	0	0	0	0
Defined Benefit Plan, Other Cost (Credit)	0	0	0	0
Settlements and curtailments	0	0	0	0
Net periodic benefit cost/(income)	65	64	130	128
UNITED STATES | Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Service cost	73	75	146	147
Interest cost	401	405	801	813
Expected return on assets	(455)	(480)	(910)	(966)
Amortization of prior service costs/(credits)	24	0	47	0
Net remeasurement (gain)/loss	0	81	0	194
Defined Benefit Plan, Other Cost (Credit)	1	10	9	12
Settlements and curtailments	0	3	0	45
Net periodic benefit cost/(income)	44	94	93	245
Foreign Plan | Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Service cost	61	61	124	122
Interest cost	233	242	468	479
Expected return on assets	(252)	(223)	(507)	(442)
Amortization of prior service costs/(credits)	6	5	12	10
Net remeasurement (gain)/loss	(172)	8	(183)	8
Defined Benefit Plan, Other Cost (Credit)	53	57	67	61
Settlements and curtailments	(3)	1	(3)	1
Net periodic benefit cost/(income)	$ (74)	$ 151	$ (22)	$ 239