Retirement Benefits - Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Pension Plan [Member] | United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 20	$ 19	$ 58	$ 59
Interest cost	29	24	88	71
Expected return on plan assets	(83)	(79)	(248)	(233)
Settlement	3	0	3	1
Amortization of net loss	4	8	11	30
Amortization of prior service credit	0	0	0	0
Net periodic benefit (income)/cost	(27)	(28)	(88)	(72)
Pension Plan [Member] | United Kingdom [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	4	9	13
Interest cost	18	14	54	42
Expected return on plan assets	(34)	(42)	(110)	(128)
Settlement	1	1	1	2
Amortization of net loss	7	7	22	21
Amortization of prior service credit	(3)	(4)	(9)	(13)
Net periodic benefit (income)/cost	(9)	(20)	(33)	(63)
Pension Plan [Member] | Other Foreign Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	6	6	17	18
Interest cost	4	3	12	9
Expected return on plan assets	(10)	(9)	(29)	(28)
Settlement	0	2	0	2
Amortization of net loss	0	1	2	4
Amortization of prior service credit	1	1	1	1
Net periodic benefit (income)/cost	1	4	3	6
PRW [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost	0	0	1	1
Expected return on plan assets	0	0	0	0
Settlement	0	0	0	0
Amortization of net loss	0	1	1	2
Amortization of prior service credit	0	(1)	(2)	(3)
Net periodic benefit (income)/cost	$ 0	$ 0	$ 0	$ 0