Stock-based Compensation - Additional Information (Detail) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
Oct. 31, 2020 USD ($) $ / shares	Oct. 31, 2020 USD ($) $ / shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Accrued share based compensation expense	$ 1.9	$ 2.8
Closing price of ordinary shares \| $ / shares	$ 54.67	$ 54.67
Stock options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation cost, stock options	$ 3.1	$ 3.1
Weighted average recognition period		2 years 4 months 13 days
Restricted stock units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation cost, restricted stock units	137.3	$ 137.3
Weighted average recognition period		2 years 6 months 14 days
Aggregate intrinsic value of unvested restricted stock units	$ 168.8	$ 168.8

Accrued share based compensation expense.

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- Definition

Closing market price of ordinary shares on NASDAQ on last day of reporting period.

+ References

No definition available.

+ Details

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- Definition

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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- Definition

Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

+ References

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- Definition

Amount of cost to be recognized for option under share-based payment arrangement.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Intrinsic value of nonvested award under share-based payment arrangement. Excludes share and unit options.

+ References

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