Income taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Operating Loss Carryforwards [Line Items]
Effective tax rate	8.10%	0.00%	0.00%
Accumulated federal net operating loss carryforward	$ 124,512	$ 100,000	$ 93,000
Valuation allowance	(35,369)	$ (29,888)
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Accumulated federal net operating loss carryforward	$ 2,924

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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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.

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