Fair Value Measurements (Notional Amounts and Fair Values of Derivatives) (Details) - USD ($) $ in Millions	Apr. 30, 2024	Jan. 31, 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	$ 10,555	$ 12,150
Fair value hedging | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	4,771	6,271
Cash flow hedges | Cross-currency swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	5,784	5,879
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	(2,075)	(1,956)
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	(777)	(654)
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	$ (1,298)	$ (1,302)