Fair Value Measurements (Notional Amounts and Fair Values of Derivatives) (Details) - USD ($) $ in Millions	Apr. 30, 2026	Jan. 31, 2026
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	$ 9,934	$ 10,791
Fair value hedging \| Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	4,771	4,771
Cash flow hedges \| Cross-currency swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	5,163	6,020
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	(1,366)	(1,331)
Recurring \| Fair value hedging \| Interest rate swap \| Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	(423)	(411)
Recurring \| Cash flow hedges \| Cross-currency swaps \| Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ (943)	$ (920)