Retirement Benefits - Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Worldwide OPEB
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Service cost	$ 10	$ 12	$ 31	$ 36
Interest cost	36	31	110	95
Expected return on assets	0	0	0	0
Amortization of prior service costs/(credits)	(1)	(3)	(2)	(9)
Net remeasurement (gain)/loss	0	0	0	0
Defined Benefit Plan, Other Cost (Credit)	1	1	0	1
Settlements and curtailments	0	0	0	0
Net periodic benefit cost/(income)	46	41	139	123
UNITED STATES | Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Service cost	125	131	375	396
Interest cost	263	232	790	694
Expected return on assets	(642)	(681)	(1,927)	(2,047)
Amortization of prior service costs/(credits)	0	1	1	2
Net remeasurement (gain)/loss	7	(40)	7	201
Defined Benefit Plan, Other Cost (Credit)	9	10	20	15
Settlements and curtailments	1	7	1	56
Net periodic benefit cost/(income)	(237)	(340)	(733)	(683)
Foreign Plan | Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Service cost	101	140	319	423
Interest cost	123	107	390	315
Expected return on assets	(245)	(283)	(772)	(852)
Amortization of prior service costs/(credits)	6	5	18	17
Net remeasurement (gain)/loss	0	0	16	(565)
Defined Benefit Plan, Other Cost (Credit)	11	23	28	107
Settlements and curtailments	0	0	0	0
Net periodic benefit cost/(income)	(4)	(8)	(1)	(555)
Foreign Plan | Pension Plan | Global Redesign
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Defined Benefit Plan, Other Cost (Credit)	$ 11	$ 22	$ 27	$ 106