v3.25.1
Postretirement Benefit Plans (Postretirement Changes Recognized in AOCI) (Details) - USD ($)
$ in Millions
12 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Pension Benefits [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Beginning balance in accumulated other comprehensive loss $ (18) $ 34
Curtailments, settlements, and special termination benefits 1 0
Net actuarial (losses) gains (20) (46)
Prior service cost 5 0
Prior service credit (2) (1)
Actuarial losses (gains) 1 (5)
Effect of currency exchange (1) 0
Total postretirement amounts recognized in accumulated other comprehensive loss (34) (18)
Other Benefits [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Beginning balance in accumulated other comprehensive loss 72 74
Curtailments, settlements, and special termination benefits 0 0
Net actuarial (losses) gains 3 4
Prior service cost 0 0
Prior service credit (4) (3)
Actuarial losses (gains) (3) (3)
Effect of currency exchange 0 0
Total postretirement amounts recognized in accumulated other comprehensive loss $ 68 $ 72