Accumulated other comprehensive income (loss) - Reclassifications out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Nov. 03, 2018	Oct. 28, 2017	Nov. 03, 2018	Oct. 28, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of sales:	$ 820.5	$ 835.8	$ 2,746.2	$ 2,689.7
Interest expense reclassification adjustment	10.6	16.6	28.9	42.7
Income before income taxes	59.1	11.1	708.6	(213.7)
Income taxes	(29.2)	(7.2)	(159.1)	45.7
Net income	29.9	3.9	549.5	(168.0)
Net curtailment gain and settlement loss	0.0	(3.7)	0.0	(3.7)
Amounts reclassified from AOCI	(0.3)	(3.4)	(0.5)	(5.4)
Gains (losses) on cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income before income taxes	(0.6)	(0.8)	(1.5)	(4.1)
Income taxes	0.1	0.2	0.5	1.0
Net income	(0.5)	(0.6)	(1.0)	(3.1)
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:	0.2	(0.8)	0.9	(3.0)
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 reclassification adjustment	(0.6)	0.0	(1.3)	0.4
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:	(0.2)	0.0	(1.1)	(1.5)
Actuarial losses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification adjustment from AOCI, pension and other postretirement benefit plans, before tax	0.3	0.7	0.6	2.2
Prior service credits
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification adjustment from AOCI, pension and other postretirement benefit plans, before tax	0.0	(0.4)	0.0	(1.3)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification adjustment from AOCI, pension and other postretirement benefit plans, before tax	0.3	(3.4)	0.6	(2.8)
Reclassification adjustment from AOCI, pension and other postretirement benefit plans, tax	(0.1)	0.6	(0.1)	0.5
Amounts reclassified from AOCI	$ 0.2	$ (2.8)	$ 0.5	$ (2.3)