LEASES - Supplemental Information Related to Operating Leases (Details) - USD ($) $ in Millions	Jul. 31, 2020	Jan. 31, 2020
Leases [Abstract]
Operating lease right of use (“ROU”) assets	$ 1,787	$ 1,780
Operating lease right of use (“ROU”) assets extensible list	us-gaap:OtherAssets
Current operating lease liabilities	$ 435	432
Current operating lease liabilities extensible list	us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent
Non-current operating lease liabilities	$ 1,383	1,360
Non-current operating lease liabilities extensible list	us-gaap:OtherLiabilitiesNoncurrent
Total operating lease liabilities	$ 1,818	$ 1,792
Weighted-average remaining lease term (in years)	8 years 5 months 19 days	8 years 6 months 25 days
Weighted-average discount rate	3.75%	3.81%