Retirement-Related Benefits (Details) - USD ($) $ in Millions	12 Months Ended
Jan. 31, 2018	Jan. 31, 2017
Contribution expense from retirement plans [Line Items]
Defined contribution plan, employer matching contribution, percent of match	100.00%
Defined contribution plan, employer matching contribution, percent of employees' gross pay	6.00%
Vesting percentage of matching contribution to eligible associates	100.00%
Defined contribution plan, maximum annual contributions per employee, percent	50.00%
United Kingdom \| Deferred income taxes and other
Contribution expense from retirement plans [Line Items]
Assets for plan benefits, defined benefit plan	$ 97
Liability, defined benefit plan, noncurrent		$ 129
Japan \| Deferred income taxes and other
Contribution expense from retirement plans [Line Items]
Liability, defined benefit plan, noncurrent	$ 184	$ 203

Amount of asset, recognized in statement of financial position, for overfunded defined benefit pension and other postretirement plans.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
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-Section 50
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Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

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Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

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Amount of liability, recognized in statement of financial position, for defined benefit pension and other postretirement plans, classified as noncurrent.

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[Line Items] for Contribution expense from retirement plans [Table]

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