Segment information - Summary of Activity by Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Nov. 03, 2018	Oct. 28, 2017	Nov. 03, 2018	Oct. 28, 2017	Feb. 03, 2018
Segment Reporting Information [Line Items]
Sales	$ 1,191.7	$ 1,156.9	$ 4,092.4	$ 3,959.9
Operating income (loss)	(48.8)	5.5	(681.1)	256.4
Goodwill and intangible impairments	0.0	0.0	448.7	0.0
Restructuring costs	9.5	0.0	35.6	0.0
Total assets	4,907.5	5,800.7	4,907.5	5,800.7	$ 5,839.6
North America
Segment Reporting Information [Line Items]
Sales	1,064.3	1,022.3	3,698.8	3,558.9
Operating income (loss)	(19.5)	53.8	(561.0)	350.2
Goodwill and intangible impairments			448.7
Restructuring costs			53.7
Transaction-related costs			160.4
Total assets	4,428.6	5,284.8	4,428.6	5,284.8	5,309.0
International
Segment Reporting Information [Line Items]
Sales	121.3	128.4	381.5	382.8
Operating income (loss)	(4.4)	(1.7)	(18.1)	(1.9)
Inventory charges			3.8
Total assets	387.1	404.8	387.1	404.8	420.3
Other
Segment Reporting Information [Line Items]
Sales	6.1	6.2	12.1	18.2
Operating income (loss)	(24.9)	(46.6)	(102.0)	(91.9)
Restructuring costs	9.5		41.3
Transaction-related costs	0.4		7.0
Total assets	$ 91.8	$ 111.1	$ 91.8	$ 111.1	$ 110.3