Retirement Benefits - Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension Plan | Global Redesign
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Other Cost (Credit)			$ 415
Settlements and curtailments			104
Worldwide OPEB
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 49	$ 47	43
Interest cost	127	169	211
Expected return on assets	0	0	0
Amortization of prior service costs/(credits)	(12)	(16)	(70)
Net remeasurement (gain)/loss	(376)	556	551
Defined Benefit Plan, Other Cost (Credit)	0	0	0
Settlements and curtailments	0	(2)	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	(212)	754	735
U.S. Plans | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	526	520	474
Interest cost	928	1,291	1,570
Expected return on assets	(2,728)	(2,795)	(2,657)
Amortization of prior service costs/(credits)	2	4	87
Net remeasurement (gain)/loss	(254)	377	(135)
Defined Benefit Plan, Other Cost (Credit)	19	35	22
Settlements and curtailments	70	5	(67)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	(1,437)	(563)	(706)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	(70)
Non-U.S. Plans | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	557	529	506
Interest cost	420	514	691
Expected return on assets	(1,130)	(1,067)	(1,124)
Amortization of prior service costs/(credits)	24	32	33
Net remeasurement (gain)/loss	(3,241)	499	2,084
Defined Benefit Plan, Other Cost (Credit)	156	226	398
Settlements and curtailments	(2)	103	8
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	(3,216)	836	2,596
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement		$ (61)
Non-U.S. Plans | Pension Plan | Global Redesign
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Other Cost (Credit)	$ 156
NETHERLANDS | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Settlements and curtailments			12
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement			$ (57)