Taxes (Reconciliation of Unrecognized Tax Benefits from Continuing Operations) (Details) - USD ($) $ in Millions	12 Months Ended
Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
Reconciliation of Unrecognized Tax Benefits
Unrecognized tax benefits, beginning of year	$ 1,010	$ 1,050	$ 607
Increases related to prior year tax positions	620	130	388
Decreases related to prior year tax positions	(107)	(254)	(32)
Increases related to current year tax positions	203	122	145
Settlements during the period	(390)	(23)	(46)
Lapse in statutes of limitations	(31)	(15)	(12)
Unrecognized tax benefits, end of year	$ 1,305	$ 1,010	$ 1,050

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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Amount of unrecognized tax benefits.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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