Debt - Schedule of Interest Expense (Detail) - USD ($) $ in Millions	12 Months Ended
Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Debt Disclosure [Abstract]
Contractual interest expense	$ 106	$ 106	$ 23
Amortization of debt issuance costs	4	16	5
Amortization of debt discount	0	4	26
Debt interest expense	$ 110	$ 126	$ 54

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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Amount of amortization expense attributable to debt issuance costs.

+ References

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No definition available.

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- Definition

Amount of the cost of borrowed funds accounted for as interest expense for debt.

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Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings, excluding amortization of debt discount (premium) and financing costs.

+ References

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