SUPPLEMENTAL CONSOLIDATED FINANCIAL INFORMATION - Trade Receivables — Allowance for Expected Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jul. 31, 2020	Jul. 31, 2020
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 144	$ 94
Provision charged to income statement	11	47
Bad debt write-offs	(9)	(22)
Balance at end of period	146	146
Adjustment for adoption of accounting standards
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 0	$ 27