DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Notional Amounts of Outstanding Derivative Instruments (Details) - USD ($) $ in Millions	Jul. 31, 2020	Jan. 31, 2020
Foreign exchange contracts
Derivative [Line Items]
Notional amount	$ 15,107	$ 16,414
Foreign exchange contracts | Designated as cash flow hedging instruments
Derivative [Line Items]
Notional amount	7,600	8,703
Foreign exchange contracts | Non-designated as hedging instruments
Derivative [Line Items]
Notional amount	7,507	7,711
Interest rate contracts | Non-designated as hedging instruments
Derivative [Line Items]
Notional amount	$ 5,333	$ 4,043