Retirement Benefits - Net Periodic Benefit Cost (Details) - Pension Plan [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Defined Benefit Plan Disclosure [Line Items]
Settlements	$ 82
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	10	$ 11
Interest cost	36	49
Expected return on plan assets	(55)	(76)
Settlements	82	0
Amortization of net loss	9	9
Amortization of prior service credit	0	0
Net periodic benefit cost/(income)	82	(7)
United Kingdom [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1
Interest cost	29	28
Expected return on plan assets	(42)	(39)
Settlements	3	0
Amortization of net loss	15	14
Amortization of prior service credit	(1)	(3)
Net periodic benefit cost/(income)	5	1
Other Foreign Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	3	4
Interest cost	6	7
Expected return on plan assets	(10)	(10)
Settlements	0	0
Amortization of net loss	0	0
Amortization of prior service credit	0	0
Net periodic benefit cost/(income)	$ (1)	$ 1