Disposals, Acquisitions and Related Items (Assets and Liabilities Held for sale) (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2021	Jan. 31, 2020
Disposal Group, Including Discontinued Operation, Liabilities [Abstract]
Current liabilities	$ 12,734	$ 0
Asda and Seiyu [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations
Disposal Group, Including Discontinued Operation, Assets [Abstract]
Cash and cash equivalents	1,848
Other current assets	2,545
Property and equipment, net	13,193
Operating lease right-of-use assets	4,360
Finance lease right-of-use assets, net	1,395
Goodwill	2,211
Other long-term assets	1,063
Valuation allowance against assets held for sale	(7,420)
Total assets held for sale	19,195
Disposal Group, Including Discontinued Operation, Liabilities [Abstract]
Current liabilities	6,535
Operating lease obligations, including amounts due within one year	4,245
Finance lease obligations, including amounts due within one year	1,495
Deferred income taxes and other	459
Total liabilities held for sale	12,734
Foreign currency translation	1,300
Asda [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations
Disposal Group, Including Discontinued Operation, Liabilities [Abstract]
Accumulated pension components included in disposal group, expected amount	$ 2,300