Retirement Benefits - Net Periodic Cost (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Amortization of:
Settlement loss	$ 0	$ 0	$ 359
Postretirement Health Care Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0
Interest cost	1	2	3
Expected return on plan assets	(11)	(10)	(10)
Amortization of:
Unrecognized net loss	3	3	4
Unrecognized prior service benefit	(5)	(15)	(15)
Settlement loss	0	0	0
Net periodic cost (benefit)	(12)	(20)	(18)
UNITED STATES
Amortization of:
Settlement loss	0	0	359
UNITED STATES | Pension Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0
Interest cost	115	144	202
Expected return on plan assets	(235)	(225)	(275)
Amortization of:
Unrecognized net loss	70	58	46
Unrecognized prior service benefit	0	0	0
Settlement loss	0	0	359
Net periodic cost (benefit)	(50)	(23)	332
Non U.S. | Pension Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	2	2
Interest cost	21	29	36
Expected return on plan assets	(99)	(85)	(85)
Amortization of:
Unrecognized net loss	16	15	15
Unrecognized prior service benefit	(3)	(3)	0
Settlement loss	0	0	0
Net periodic cost (benefit)	$ (64)	$ (42)	$ (32)