Accumulated other comprehensive income (loss) - Reclassifications out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	May 04, 2019	May 05, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of sales	$ (932.3)	$ (995.8)
Interest expense, net	(9.2)	(8.9)
Income before income taxes	11.5	582.5
Other non-operating income	0.3	0.6
Income taxes	(1.5)	(85.9)
Net income	10.0	496.6
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net income	(0.2)	(0.1)
Gains (losses) on cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income before income taxes	(0.5)	(0.5)
Income taxes	0.1	0.2
Net income	(0.4)	(0.3)
Gains (losses) on cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income | Foreign currency contracts
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of sales	(0.3)	0.3
Gains (losses) on cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income | Interest rate swaps
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest expense, net	(0.6)	(0.3)
Gains (losses) on cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income | Commodity contracts
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of sales	0.4	(0.5)
Actuarial losses | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other non-operating income	(0.3)	(0.3)
Prior service credits | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other non-operating income	0.0	0.1
Accumulated Defined Benefit Plans Adjustment Attributable to Parent | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income before income taxes	0.3	0.2
Income taxes	(0.1)	0.0
Net income	$ 0.2	$ 0.2