Fair Value Measurements (Notional Amounts And Fair Values Of Interest Rate Swaps) (Details) - USD ($) $ in Millions	Jul. 31, 2021	Jan. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	$ 11,493	$ 9,573
Fair value hedging | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	3,250	3,250
Net investment hedging | Cross-currency swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	0	1,250
Cash flow hedges | Cross-currency swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	8,243	5,073
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	(483)	83
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	133	166
Recurring | Net investment hedging | Cross-currency swaps | Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	311
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	$ (616)	$ (394)