v3.26.1
Postretirement Benefit Plans (Postretirement Changes Recognized in AOCI) (Details) - USD ($)
$ in Millions
12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Pension Benefits [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Beginning balance in accumulated other comprehensive loss $ (34) $ (18)
Curtailments, settlements, and special termination benefits 0 1
Net actuarial gains (losses) 46 (20)
Prior service cost (1) 5
Prior service credit (2) (2)
Actuarial losses (gains) 2 1
Effect of currency exchange (1) (1)
Total postretirement amounts recognized in accumulated other comprehensive loss 10 (34)
Other Benefits [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Beginning balance in accumulated other comprehensive loss 68 72
Curtailments, settlements, and special termination benefits (5) 0
Net actuarial gains (losses) 10 3
Prior service cost 0 0
Prior service credit (3) (4)
Actuarial losses (gains) (3) (3)
Effect of currency exchange 1 0
Total postretirement amounts recognized in accumulated other comprehensive loss $ 68 $ 68