Retirement plans - Components of UK Net Asset Recognized (Details) - USD ($) $ in Millions	Jan. 30, 2021	Feb. 01, 2020
Pension plan \| Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Other assets (non current)	$ 51.6	$ 38.5

Amount of asset, recognized in statement of financial position, for overfunded defined benefit pension and other postretirement plans.

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Name:	us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant