FAIR VALUE MEASUREMENTS AND INVESTMENTS - Hierarchy for Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Jul. 31, 2020	Jan. 31, 2020
Assets:
Equity and other securities	$ 1	$ 12
Derivative instruments	338	81
Total assets	6,304	4,714
Liabilities:
Derivative instruments	319	68
Total liabilities	319	68
Money market funds
Assets:
Cash and cash equivalents	5,965	4,621
Level 1
Assets:
Equity and other securities	1	12
Derivative instruments	0	0
Total assets	5,966	4,633
Liabilities:
Derivative instruments	0	0
Total liabilities	0	0
Level 1 | Money market funds
Assets:
Cash and cash equivalents	5,965	4,621
Level 2
Assets:
Equity and other securities	0	0
Derivative instruments	338	81
Total assets	338	81
Liabilities:
Derivative instruments	319	68
Total liabilities	319	68
Level 2 | Money market funds
Assets:
Cash and cash equivalents	0	0
Level 3
Assets:
Equity and other securities	0	0
Derivative instruments	0	0
Total assets	0	0
Liabilities:
Derivative instruments	0	0
Total liabilities	0	0
Level 3 | Money market funds
Assets:
Cash and cash equivalents	$ 0	$ 0