Accumulated other comprehensive income (loss) - Reclassifications out of AOCI (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Aug. 01, 2015	Aug. 02, 2014	Aug. 01, 2015	Aug. 02, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification adjustment of losses to net income		$ 1.1	$ 5.1	$ 1.8	$ 12.5
Reclassification adjustment of losses to net income		(0.3)	(1.7)	(0.5)	(4.4)
Reclassification adjustment of losses to net income		0.8	3.4	1.3	8.1
Reclassification adjustment from AOCI, pension and other postretirement benefit plans, before tax		0.3	0.0	0.6	0.1
Reclassification adjustment from AOCI, pension and other postretirement benefit plans, tax		(0.1)	0.0	(0.1)	0.0
Reclassification adjustment from AOCI, pension and other postretirement benefit plans, net of tax		0.2	0.0	0.5	0.1
Amounts reclassified from AOCI		1.0	3.4	1.8	8.2
Foreign currency contracts | Cost of Sales
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification adjustment of losses to net income		0.0	0.3	0.1	0.3
Interest rate swaps | Interest expense, net
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification adjustment of losses to net income		0.8	0.0	1.1	0.0
Commodity contracts | Cost of Sales
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification adjustment of losses to net income		0.3	4.8	0.6	12.2
Amortization of unrecognized net prior service credit | Selling, General and Administrative Expenses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification adjustment from AOCI, pension and other postretirement benefit plans, before tax	[1]	(0.6)	(0.5)	(1.1)	(0.9)
Amortization of unrecognized actuarial loss | Selling, General and Administrative Expenses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification adjustment from AOCI, pension and other postretirement benefit plans, before tax	[1]	$ 0.9	$ 0.5	$ 1.7	$ 1.0

[1] These items are included in the computation of net periodic pension benefit (cost). See Note 16 for additional information.