Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning of period	$ 852	$ 304	$ 231
Tax Positions taken in prior period, gross increases	12	474	31
Tax positions taken in prior period, gross decreases	(37)	(2)	(6)
Tax Positions taken in current period, gross increases	640	107	51
Settlements	(27)	(15)	(1)
Lapse of statute of limitations	(4)	(10)	(8)
Currency translation effect	(3)	(6)
Currency translation effect			6
End of period	$ 1,433	$ 852	$ 304

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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- Definition

Amount of unrecognized tax benefits.

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Amount of decrease in unrecognized tax benefits resulting from foreign currency translation.

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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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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