Taxes (Schedule of Deferred Tax Classification in the Balance Sheet) (Details) - USD ($) $ in Millions	Jan. 31, 2020	Jan. 31, 2019
Liabilities [Abstract]
Net deferred tax liabilities	$ 4,290	$ 4,500
Other long-term assets
Assets
Other assets and deferred charges	1,914	1,796
Deferred income taxes and other
Liabilities [Abstract]
Deferred income taxes and other	$ 6,204	$ 6,296

Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, with jurisdictional netting and classified as noncurrent.

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
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Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
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Reference 3: http://fasb.org/us-gaap/role/ref/otherTransitionRef
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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