Segment information - Summary of Activity by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 29, 2022	Jan. 30, 2021	Feb. 01, 2020
Segment Reporting Information [Line Items]
Total sales	$ 7,826.0	$ 5,226.9	$ 6,137.1
Operating income (loss)	903.4	(57.7)	158.3
Interest expense, net	(16.9)	(32.0)	(35.6)
Other non-operating (loss) income	(2.1)	0.0	7.0
Income (loss) before income taxes	884.4	(89.7)	129.7
Depreciation and amortization	163.5	176.0	178.0
Capital additions	129.6	83.0	136.3
Asset impairments	1.5	159.0	47.7
Restructuring charges	(3.3)	46.2	69.9
Charge related to litigation settlement	1.7	7.5	33.2
Total assets	6,575.1	6,178.9
Total long-lived assets	1,374.7	1,022.5
Diamonds Direct USA Inc.
Segment Reporting Information [Line Items]
Acquisition related costs	5.0
Corporate and unallocated
Segment Reporting Information [Line Items]
Operating income (loss)	(92.2)	(72.0)	(119.7)
Restructuring charges	(2.3)	0.5	20.8
Charge related to litigation settlement	1.7	7.5	33.2
Total assets	515.6	517.9
North America
Segment Reporting Information [Line Items]
Total sales	7,264.8	4,840.9	5,565.8
North America | Operating Segments
Segment Reporting Information [Line Items]
Total sales	7,264.8	4,840.9	5,565.8
Operating income (loss)	981.4	57.9	284.9
Depreciation and amortization	149.2	163.7	159.9
Capital additions	112.6	79.0	128.3
Asset impairments	2.0	136.7	47.7
Gain from sale of customer in-house finance receivable	1.4
Restructuring charges	(1.0)
Inventory charges		1.6	6.0
Severance costs		36.0	42.1
Total assets	5,540.1	5,101.9
Total long-lived assets	1,328.4	978.1
North America | Operating Segments | Diamonds Direct USA Inc. and Rocksbox
Segment Reporting Information [Line Items]
Acquisition related costs	6.4
North America | Operating Segments | Fair Value Adjustment to Inventory | Diamonds Direct USA Inc.
Segment Reporting Information [Line Items]
Operating income (loss)	(5.4)
North America | Canada | Operating Segments
Segment Reporting Information [Line Items]
Total sales	206.2	150.9	204.6
International
Segment Reporting Information [Line Items]
Total sales	492.4	355.9	518.0
International | Operating Segments
Segment Reporting Information [Line Items]
Total sales	492.4	355.9	518.0
Operating income (loss)	14.4	(43.3)	9.0
Depreciation and amortization	14.0	12.0	17.8
Capital additions	16.6	4.0	8.0
Asset impairments	(0.5)	22.3
Severance costs		9.7	7.0
Total assets	438.2	514.2
Total long-lived assets	43.4	41.6
Other
Segment Reporting Information [Line Items]
Total sales	68.8	30.1	53.3
Other | Operating Segments
Segment Reporting Information [Line Items]
Total sales	68.8	30.1	53.3
Operating income (loss)	(0.2)	(0.3)	(15.9)
Depreciation and amortization	0.3	0.3	0.3
Capital additions	0.4	0.0	0.0
Inventory charges		(0.2)	$ 3.2
Total assets	81.2	44.9
Total long-lived assets	$ 2.9	$ 2.8