v3.26.3
Retirement Benefits - Net Periodic Benefit Cost (Details) - Pension Plan [Member] - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Mar. 31, 2025
Sep. 30, 2026
Sep. 30, 2025
Defined Benefit Plan Disclosure [Line Items]          
Settlement (gain)/expense $ 11     $ 11 $ 82
United States [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Service cost 9 $ 10   26 30
Interest cost 41 32   124 100
Expected return on plan assets (63) (51)   (189) (157)
Settlement (gain)/expense 0 1 $ 82 0 83
Amortization of net loss 18 7   54 23
Amortization of prior service credit 0 0   0 0
Net periodic benefit cost/(income) 5 (1)   15 79
United Kingdom [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Service cost 1 1   4 4
Interest cost 30 31   90 91
Expected return on plan assets (48) (44)   (143) (131)
Settlement (gain)/expense 0 0   0 3
Amortization of net loss 17 16   49 47
Amortization of prior service credit 1 (2)   3 (4)
Net periodic benefit cost/(income) 1 2   3 10
Other Foreign Plans [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Service cost 3 3   9 10
Interest cost 6 7   20 20
Expected return on plan assets (12) (12)   (36) (34)
Settlement (gain)/expense (11) 0   (6) 0
Amortization of net loss 0 1   0 1
Amortization of prior service credit 1 0   1 0
Net periodic benefit cost/(income) $ (13) $ (1)   $ (12) $ (3)