Accumulated other comprehensive income (loss) - Reclassifications out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	May 01, 2021	May 02, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of sales	$ 1,010.4	$ 648.3
Other operating income, net	3.1	3.6
Other non-operating income, net	0.1	0.1
Income before income taxes	164.9	(306.6)
Income taxes	(26.5)	109.5
Net income (loss)	138.4	(197.1)
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net income (loss)	0.4	(7.8)
Losses (gains) on cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net income (loss)	0.2	(8.1)
Losses (gains) on cash flow hedges, excluding dedesignated | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income before income taxes	0.2	(0.8)
Losses (gains) on cash flow hedges, excluding dedesignated | Reclassification out of Accumulated Other Comprehensive Income | Foreign currency contracts
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of sales	0.1	0.0
Losses (gains) on cash flow hedges, excluding dedesignated | Reclassification out of Accumulated Other Comprehensive Income | Commodity contracts
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of sales	0.1	(0.8)
Losses (gains) on dedesignating cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income before income taxes	0.0	(9.9)
Income taxes	0.0	2.6
Losses (gains) on dedesignating cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income | Foreign currency contracts
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other operating income, net	0.0	(0.6)
Losses (gains) on dedesignating cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income | Commodity contracts
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other operating income, net	0.0	(9.3)
Defined benefit pension plan items | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income before income taxes	0.2	0.3
Income taxes	0.0	0.0
Net income (loss)	0.2	0.3
Actuarial gains (losses) | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other non-operating income, net	0.2	0.1
Prior service credits (costs) | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other non-operating income, net	$ 0.0	$ 0.2