FINANCIAL SERVICES - Schedule of Financing Receivables Held by the Consolidated VIEs (Details) - USD ($) $ in Millions	Jul. 31, 2020	Jan. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Assets held by consolidated VIEs, net	$ 121,276	$ 118,861
Variable Interest Entity, Primary Beneficiary
Accounts, Notes, Loans and Financing Receivable [Line Items]
Assets held by consolidated VIEs, net	7,182	6,664
Short-term, net | Variable Interest Entity, Primary Beneficiary
Accounts, Notes, Loans and Financing Receivable [Line Items]
Assets held by consolidated VIEs, net	3,315	3,316
Long-term, net | Variable Interest Entity, Primary Beneficiary
Accounts, Notes, Loans and Financing Receivable [Line Items]
Assets held by consolidated VIEs, net	$ 3,867	$ 3,348