Income taxes (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Aug. 02, 2019	Aug. 03, 2018	Aug. 02, 2019	Aug. 03, 2018
Income taxes
Reserves for uncertain tax benefits	$ 5.0		$ 5.0
Interest accrued related to uncertain tax benefits	1.0		1.0
Potential penalties accrued related to uncertain tax benefits	0.9		0.9
Reserves for uncertain tax benefits included in noncurrent Other liabilities	6.9		6.9
Reserve for uncertain tax positions that would impact effective tax rate if recognized	$ 5.0		$ 5.0
Effective income tax rates (as a percent)	22.90%	21.50%	21.90%	21.60%

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

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Amount recognized for uncertainty in income taxes classified as noncurrent.

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Amount of unrecognized tax benefits.

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Amount of statutory penalties accrued for a tax position claimed or expected to be claimed by the entity, in its tax return.

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Amount of interest expense accrued for an underpayment of income taxes.

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