Segment information - Schedule of Activity by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 28, 2023	Jan. 29, 2022	Jan. 30, 2021
Segment Reporting Information [Line Items]
Total sales	$ 7,842.1	$ 7,826.0	$ 5,226.9
Operating income (loss)	604.9	903.4	(57.7)
Interest expense, net	(13.5)	(16.9)	(32.0)
Other non-operating expense, net	(140.2)	(2.1)	0.0
Income before income taxes	451.2	884.4	(89.7)
Depreciation and amortization	164.5	163.5	176.0
Capital additions	138.9	129.6	83.0
Litigation settlement, expense	203.8	1.7	7.5
Asset impairments	22.7	1.5	159.0
Restructuring charges	0.0	(3.3)	46.2
Total assets	6,620.4	6,575.1
Total long-lived assets	1,745.6	1,374.7
Blue Nile
Segment Reporting Information [Line Items]
Acquisition related costs	4.2
Diamonds Direct
Segment Reporting Information [Line Items]
Acquisition related costs		5.0
Corporate and unallocated
Segment Reporting Information [Line Items]
Operating income (loss)	(70.5)	(92.2)	(72.0)
Litigation settlement, expense		(1.7)	(7.5)
Restructuring charges		(2.3)	0.5
Total assets	190.7	515.6
North America
Segment Reporting Information [Line Items]
Total sales	7,289.5	7,264.8	4,840.9
North America | Reportable segments
Segment Reporting Information [Line Items]
Total sales	7,289.5	7,264.8	4,840.9
Operating income (loss)	673.2	981.4	57.9
Depreciation and amortization	153.8	149.2	163.7
Capital additions	127.6	112.6	79.0
Litigation settlement, expense	203.8
Asset impairments	20.0	2.0	136.7
Gain from sale of customer in-house finance receivable		1.4
Restructuring charges		(1.0)
Inventory charges			(1.6)
Severance costs			36.0
Total assets	5,901.5	5,540.1
Total long-lived assets	1,702.5	1,328.4
North America | Reportable segments | Diamonds Direct and Blue Nile
Segment Reporting Information [Line Items]
Acquisition related costs	13.4
North America | Reportable segments | Blue Nile
Segment Reporting Information [Line Items]
Acquisition related costs	14.7
North America | Reportable segments | Diamonds Direct and Rocksbox
Segment Reporting Information [Line Items]
Acquisition related costs		6.4
North America | Reportable segments | Fair Value Adjustment to Inventory | Diamonds Direct
Segment Reporting Information [Line Items]
Acquisition related costs		5.4
North America | Canada | Reportable segments
Segment Reporting Information [Line Items]
Total sales	209.1	206.2	150.9
International
Segment Reporting Information [Line Items]
Total sales	470.1	492.4	355.9
International | Reportable segments
Segment Reporting Information [Line Items]
Total sales	470.1	492.4	355.9
Operating income (loss)	(0.2)	14.4	(43.3)
Depreciation and amortization	10.3	14.0	12.0
Capital additions	10.9	16.6	4.0
Asset impairments	2.7	(0.5)	22.3
Severance costs			9.7
Total assets	405.9	438.2
Total long-lived assets	40.2	43.4
Other
Segment Reporting Information [Line Items]
Total sales	82.5	68.8	30.1
Other | Reportable segments
Segment Reporting Information [Line Items]
Total sales	82.5	68.8	30.1
Operating income (loss)	2.4	(0.2)	(0.3)
Depreciation and amortization	0.4	0.3	0.3
Capital additions	0.4	0.4	0.0
Inventory charges			$ 0.2
Total assets	122.3	81.2
Total long-lived assets	$ 2.9	$ 2.9