Segment information - Summary of Activity by Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 30, 2021	Oct. 31, 2020	Oct. 30, 2021	Oct. 31, 2020
Segment Reporting Information [Line Items]
Sales	$ 1,537.8	$ 1,300.3	$ 5,014.7	$ 3,040.4
Operating income (loss)	106.9	39.7	501.0	(349.6)
Interest expense, net	(4.1)	(9.1)	(12.4)	(25.6)
Other non-operating expense, net	(1.1)	0.0	(0.9)	0.3
Income before income taxes	101.7	30.6	487.7	(374.9)
Restructuring charges	(1.7)	3.6	(3.3)	45.2
Asset impairments, net	0.7	1.5	2.0	158.1
North America
Segment Reporting Information [Line Items]
Sales	1,394.2	1,182.7	4,657.9	2,786.8
International
Segment Reporting Information [Line Items]
Sales	120.9	106.9	309.0	232.8
Other
Segment Reporting Information [Line Items]
Sales	22.7	10.7	47.8	20.8
Inventory write-down		0.2
Reportable segments | North America
Segment Reporting Information [Line Items]
Sales	1,394.2	1,182.7	4,657.9	2,786.8
Operating income (loss)	123.8	52.9	573.1	(238.3)
Acquisition and integration related costs			1.1
Gain on sale of financing receivable			1.4
Restructuring charges			(1.0)
Asset impairments, net	0.7	1.5	2.0	136.9
Inventory write-down		2.2		1.6
Severance costs		0.7		37.3
Reportable segments | North America | Diamonds Direct USA Inc.
Segment Reporting Information [Line Items]
Acquisition and integration related costs	2.6		2.6
Reportable segments | International
Segment Reporting Information [Line Items]
Sales	120.9	106.9	309.0	232.8
Operating income (loss)	0.2	1.6	(4.0)	(52.6)
Asset impairments, net				21.2
Severance costs		3.0		7.6
Reportable segments | Other
Segment Reporting Information [Line Items]
Sales	22.7	10.7	47.8	20.8
Operating income (loss)	(0.4)	1.3	(1.4)	0.8
Corporate and unallocated expenses
Segment Reporting Information [Line Items]
Operating income (loss)	(16.7)	$ (16.1)	(66.7)	(59.5)
Restructuring charges	$ (1.7)		$ (2.3)	(0.1)
Inventory write-down				0.2
Severance costs				0.3
Net charge related to litigation settlement				$ 7.5