v3.25.4
Derivative Instruments - Notional Balances and Fair Values of Derivatives (Detail) - USD ($)
$ in Millions
Dec. 31, 2025
Mar. 31, 2025
Derivatives, Fair Value [Line Items]    
Assets $ 898 $ 389
Collateral posted/held 24 43
Counterparty netting adjustment (558) (429)
Net derivative assets 364 3
Liabilities 719 1,120
Collateral posted/held (3) 0
Counterparty netting adjustment (558) (429)
Net derivative liabilities 158 691
Interest rate swaps    
Derivatives, Fair Value [Line Items]    
Notional balances 75,036 73,058
Assets 351 338
Net derivative assets 351 338
Liabilities 544 676
Net derivative liabilities 544 676
Cross currency swaps    
Derivatives, Fair Value [Line Items]    
Notional balances 10,807 8,225
Assets 547 51
Net derivative assets 547 51
Liabilities 175 444
Net derivative liabilities $ 175 $ 444