Stockholders' Equity - Summary of Restricted Stock Unit (RSU) Activity (Detail) - Restricted Stock Units (RSUs)	3 Months Ended
Apr. 30, 2021 $ / shares shares
Unreleased restricted stock units
Beginning Balance (in shares) \| shares	1,032,215
RSUs granted (in shares) \| shares	394,324
RSUs vested (in shares) \| shares	(258,511)
RSUs forfeited/cancelled (in shares) \| shares	(16,277)
Ending Balance (in shares) \| shares	1,151,751
Weighted average grant date fair value
Beginning Balance (in usd per share) \| $ / shares	$ 121.98
RSUs granted (in usd per share) \| $ / shares	278.17
RSUs vested (in usd per share) \| $ / shares	135.23
RSUs forfeited/cancelled (in usd per share) \| $ / shares	138.00
Ending Balance (in usd per share) \| $ / shares	$ 172.24

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
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- Definition

Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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-Paragraph 2
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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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-Publisher FASB
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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

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

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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-Publisher FASB
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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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