Income taxes (Details) - USD ($) $ in Millions	3 Months Ended
	May 01, 2020	May 03, 2019
Income taxes
Reserves for uncertain tax benefits	$ 5.0
Interest accrued related to uncertain tax benefits	0.5
Potential penalties accrued related to uncertain tax benefits	0.0
Reserves for uncertain tax benefits included in noncurrent Other liabilities	5.5
Reserve for uncertain tax positions that would impact effective tax rate if recognized	$ 5.0
Effective income tax rates (as a percent)	22.20%	20.80%