Segment information - Schedule of Activity by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 29, 2023	Jul. 30, 2022	Jul. 29, 2023	Jul. 30, 2022
Segment Reporting Information [Line Items]
Total sales	$ 1,613.6	$ 1,754.9	$ 3,281.6	$ 3,593.2
Operating income (loss):	90.2	186.8	191.9	187.0
Interest income (expense), net	1.8	(3.4)	7.4	(7.8)
Other non-operating income (expense), net	0.3	(2.4)	(0.1)	(136.9)
Income before income taxes	92.3	181.0	199.2	42.3
Asset impairments, net	3.8	(0.2)	5.6	0.1
Restructuring charges	4.2	0.0	4.2	0.0
Litigation settlement, expense	0.0	0.0	(3.0)	190.0
Corporate and unallocated expenses
Segment Reporting Information [Line Items]
Operating income (loss):	(18.9)	(23.1)	(34.3)	(44.3)
North America
Segment Reporting Information [Line Items]
Total sales	1,501.1	1,616.4	3,062.3	3,321.4
North America | Reportable segments
Segment Reporting Information [Line Items]
Total sales	1,501.1	1,616.4	3,062.3	3,321.4
Operating income (loss):	117.1	210.1	241.8	234.9
Asset impairments, net	3.8		5.6
Restructuring charges	4.2		4.2
Litigation settlement, expense			(3.0)	190.0
North America | Reportable segments | Blue Nile
Segment Reporting Information [Line Items]
Acquisition and integration related costs	4.8	2.6	12.6	2.6
North America | Reportable segments | Diamonds Direct USA Inc. | Fair Value Adjustment to Inventory
Segment Reporting Information [Line Items]
Acquisition and integration related costs		5.8		10.2
International
Segment Reporting Information [Line Items]
Total sales	102.0	111.6	195.0	221.6
International | Reportable segments
Segment Reporting Information [Line Items]
Total sales	102.0	111.6	195.0	221.6
Operating income (loss):	(7.0)	(2.0)	(13.9)	(8.4)
Other
Segment Reporting Information [Line Items]
Total sales	10.5	26.9	24.3	50.2
Other | Reportable segments
Segment Reporting Information [Line Items]
Total sales	10.5	26.9	24.3	50.2
Operating income (loss):	$ (1.0)	$ 1.8	$ (1.7)	$ 4.8