Segment information - Summary of Activity by Segment (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
Aug. 03, 2019	Feb. 02, 2019	Aug. 04, 2018	May 05, 2018	Aug. 03, 2019	Aug. 04, 2018	Feb. 02, 2019
Segment Reporting Information [Line Items]
Sales	$ 1,364.4		$ 1,420.1		$ 2,796.1	$ 2,900.7
Operating income (loss)	(22.4)		(58.1)		(25.0)	(632.3)
Impairment	47.7	$ 286.7			47.7		$ 521.2
Restructuring charges					14.0	77.4
Credit transaction, net					0.0	160.4
Goodwill and intangible impairments	47.7		0.0		47.7	448.7
Total assets	5,965.6	4,420.1	4,740.8		5,965.6	4,740.8	4,420.1
North America
Segment Reporting Information [Line Items]
Sales	1,241.0		1,286.7		2,541.3	2,634.5
Operating income (loss)	24.2		(4.2)		72.3	(541.5)
Impairment	47.7	208.8		$ 308.8	47.7		517.6
Restructuring charges	1.7		53.7		1.2	53.7
Credit transaction, net			19.4			160.4
Total assets	5,226.8	3,943.0	4,171.9		5,226.8	4,171.9	3,943.0
International
Segment Reporting Information [Line Items]
Sales	113.9		131.5		225.4	260.2
Operating income (loss)	(1.0)		(6.1)		(9.0)	(13.7)
Restructuring charges			3.8			3.8
Total assets	521.1	367.4	366.6		521.1	366.6	367.4
Other
Segment Reporting Information [Line Items]
Sales	9.5		1.9		29.4	6.0
Operating income (loss)	(45.6)		(47.8)		(88.3)	(77.1)
Impairment					0.0		3.6
Restructuring charges	26.1		4.5		53.4	6.6
Transaction-related costs			25.3			31.8
Total assets	$ 217.7	$ 109.7	$ 202.3		$ 217.7	$ 202.3	$ 109.7

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