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Income taxes - Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
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May 02, 2020 | Oct. 31, 2020
Income Tax Disclosure [Abstract] |  |
CARES Act, income tax benefit on Tax Cuts and Jobs Act |  | $ 73.8
CARES Act, income tax benefit on net operating losses |  | $ 23.5
Increase in valuation allowance | $ 66.9 |

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- Definition CARES Act, Income Tax Expense (Benefit) on Net Operating Losses + References No definition available. + Details
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- Definition CARES Act, Income Tax Expense (Benefit) on Tax Cuts and Jobs Act + References No definition available. + Details
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- Definition Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319 + Details
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