Shareholders' Equity (Schedule of Fair Value of Restricted Stock) (Details) - USD ($) $ in Millions	12 Months Ended
Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2019
Restricted Stock [Member]
Additional information related to restricted stock and performance share awards and restricted stock units
Fair value	$ 597	$ 442	$ 386
Unrecognized compensation cost	$ 1,062	$ 1,096	$ 1,002
Weighted average remaining period to expense, (years)	1 year 1 month 6 days	1 year 3 months 18 days	1 year 7 months 6 days
Restricted Stock And Performance Share Awards [Member]
Additional information related to restricted stock and performance share awards and restricted stock units
Fair value	$ 275	$ 365	$ 183
Unrecognized compensation cost	$ 344	$ 326	$ 362
Weighted average remaining period to expense, (years)	1 year 4 months 24 days	1 year 4 months 24 days	1 year 1 month 6 days

Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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- Definition

Weighted average remaining contractual term for equity-based awards excluding options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 2
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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