Accumulated other comprehensive income (loss) - Reclassifications out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Feb. 02, 2019	Nov. 03, 2018	Aug. 04, 2018	May 05, 2018	Feb. 03, 2018	Oct. 28, 2017	Jul. 29, 2017	Apr. 29, 2017	Feb. 02, 2019	Feb. 03, 2018	Jan. 28, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of sales									$ 4,024.1	$ 4,063.0	$ 4,047.6
Interest expense reclassification adjustment									39.7	52.7	49.4
Income before income taxes									802.6	(527.2)	(713.8)
Income taxes									(145.2)	7.9	170.6
Net income (loss)	$ 116.2	$ 38.1	$ 31.2	$ 504.8	$ (343.0)	$ 12.1	$ (85.2)	$ (70.3)	657.4	(519.3)	(543.2)
Other non-operating income									1.7	0.0	0.0
Net income (loss) attributable to common shareholders									(690.3)	486.4	531.3
Amounts reclassified from AOCI									(0.8)	(5.4)	(0.9)
Reclassification out of AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net curtailment gain and settlement loss									0.0	(3.7)	0.0
Reclassification out of AOCI | Gains (losses) on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income before income taxes									(2.1)	(4.6)	(0.7)
Income taxes									0.6	1.1	0.1
Net income (loss)									(1.5)	(3.5)	(0.6)
Reclassification out of AOCI | Actuarial gains (losses)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other non-operating income									(0.9)	(2.8)	(1.5)
Reclassification out of AOCI | Prior service credits (costs)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other non-operating income									0.0	1.4	1.9
Reclassification out of AOCI | Accumulated defined benefit plans adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income taxes									(0.2)	0.4	0.1
Total before income tax									(0.9)	2.3	0.4
Net income (loss) attributable to common shareholders									(0.7)	1.9	0.3
Reclassification out of AOCI | Foreign currency contracts | Gains (losses) on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of sales									0.7	(3.2)	(2.7)
Reclassification out of AOCI | Interest rate swaps | Gains (losses) on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest expense reclassification adjustment									(1.9)	0.3	2.2
Reclassification out of AOCI | Commodity contracts | Gains (losses) on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of sales									$ (0.9)	$ (1.7)	$ (0.2)