Revenue recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Aug. 01, 2020	Aug. 03, 2019	Aug. 01, 2020	Aug. 03, 2019
Disaggregation of Revenue [Line Items]
Sales	$ 888.0	$ 1,364.4	$ 1,740.1	$ 2,796.1
Bridal
Disaggregation of Revenue [Line Items]
Sales	445.9	607.6	788.1	1,250.9
Fashion
Disaggregation of Revenue [Line Items]
Sales	307.2	456.6	617.7	946.4
Watches
Disaggregation of Revenue [Line Items]
Sales	46.1	92.3	88.2	174.5
Other
Disaggregation of Revenue [Line Items]
Sales	88.8	207.9	246.1	424.3
Store
Disaggregation of Revenue [Line Items]
Sales	613.9	1,198.0	1,295.2	2,455.5
Kay
Disaggregation of Revenue [Line Items]
Sales	325.0	532.5	658.5	1,111.8
Zales
Disaggregation of Revenue [Line Items]
Sales	185.1	279.7	367.4	568.5
Jared
Disaggregation of Revenue [Line Items]
Sales	168.5	254.6	313.9	509.6
Piercing Pagoda
Disaggregation of Revenue [Line Items]
Sales	59.3	74.2	110.7	156.8
James Allen
Disaggregation of Revenue [Line Items]
Sales	64.3	53.6	108.1	105.6
Peoples
Disaggregation of Revenue [Line Items]
Sales	20.8	46.4	45.5	89.0
International segment
Disaggregation of Revenue [Line Items]
Sales	61.0	113.9	125.9	225.4
Other
Disaggregation of Revenue [Line Items]
Sales	4.0	9.5	10.1	29.4
E-commerce
Disaggregation of Revenue [Line Items]
Sales	270.1	156.9	434.8	311.2
Other
Disaggregation of Revenue [Line Items]
Sales	4.0	9.5	10.1	29.4
North America
Disaggregation of Revenue [Line Items]
Sales	823.0	1,241.0	1,604.1	2,541.3
North America | Bridal
Disaggregation of Revenue [Line Items]
Sales	417.1	560.3	731.2	1,155.0
North America | Fashion
Disaggregation of Revenue [Line Items]
Sales	294.5	435.4	592.4	902.8
North America | Watches
Disaggregation of Revenue [Line Items]
Sales	23.7	53.0	48.3	101.2
North America | Other
Disaggregation of Revenue [Line Items]
Sales	87.7	192.3	232.2	382.3
North America | Store
Disaggregation of Revenue [Line Items]
Sales	574.6	1,097.2	1,206.5	2,254.5
North America | Kay
Disaggregation of Revenue [Line Items]
Sales	325.0	532.5	658.5	1,111.8
North America | Zales
Disaggregation of Revenue [Line Items]
Sales	185.1	279.7	367.4	568.5
North America | Jared
Disaggregation of Revenue [Line Items]
Sales	168.5	254.6	313.9	509.6
North America | Piercing Pagoda
Disaggregation of Revenue [Line Items]
Sales	59.3	74.2	110.7	156.8
North America | James Allen
Disaggregation of Revenue [Line Items]
Sales	64.3	53.6	108.1	105.6
North America | Peoples
Disaggregation of Revenue [Line Items]
Sales	20.8	46.4	45.5	89.0
North America | International segment
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
North America | Other
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
North America | E-commerce
Disaggregation of Revenue [Line Items]
Sales	248.4	143.8	397.6	286.8
North America | Other
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
International segment
Disaggregation of Revenue [Line Items]
Sales	61.0	113.9	125.9	225.4
International segment | Bridal
Disaggregation of Revenue [Line Items]
Sales	28.8	47.3	56.9	95.9
International segment | Fashion
Disaggregation of Revenue [Line Items]
Sales	12.7	21.2	25.3	43.6
International segment | Watches
Disaggregation of Revenue [Line Items]
Sales	22.4	39.3	39.9	73.3
International segment | Other
Disaggregation of Revenue [Line Items]
Sales	(2.9)	6.1	3.8	12.6
International segment | Store
Disaggregation of Revenue [Line Items]
Sales	39.3	100.8	88.7	201.0
International segment | Kay
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
International segment | Zales
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
International segment | Jared
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
International segment | Piercing Pagoda
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
International segment | James Allen
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
International segment | Peoples
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
International segment | International segment
Disaggregation of Revenue [Line Items]
Sales	61.0	113.9	125.9	225.4
International segment | Other
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
International segment | E-commerce
Disaggregation of Revenue [Line Items]
Sales	21.7	13.1	37.2	24.4
International segment | Other
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
Other
Disaggregation of Revenue [Line Items]
Sales	4.0	9.5	10.1	29.4
Other | Bridal
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
Other | Fashion
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
Other | Watches
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
Other | Other
Disaggregation of Revenue [Line Items]
Sales	4.0	9.5	10.1	29.4
Other | Store
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
Other | Kay
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
Other | Zales
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
Other | Jared
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
Other | Piercing Pagoda
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
Other | James Allen
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
Other | Peoples
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
Other | International segment
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
Other | Other
Disaggregation of Revenue [Line Items]
Sales	4.0	9.5	10.1	29.4
Other | E-commerce
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0	0.0	0.0
Other | Other
Disaggregation of Revenue [Line Items]
Sales	$ 4.0	$ 9.5	$ 10.1	$ 29.4