Revenue recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	May 02, 2020	May 04, 2019
Disaggregation of Revenue [Line Items]
Sales	$ 852.1	$ 1,431.7
Bridal
Disaggregation of Revenue [Line Items]
Sales	342.2	643.3
Fashion
Disaggregation of Revenue [Line Items]
Sales	310.5	489.8
Watches
Disaggregation of Revenue [Line Items]
Sales	42.1	82.2
Other
Disaggregation of Revenue [Line Items]
Sales	157.3	216.4
Store
Disaggregation of Revenue [Line Items]
Sales	681.3	1,257.5
Kay
Disaggregation of Revenue [Line Items]
Sales	333.5	579.3
Zales
Disaggregation of Revenue [Line Items]
Sales	182.3	288.8
Jared
Disaggregation of Revenue [Line Items]
Sales	145.4	255.0
Piercing Pagoda
Disaggregation of Revenue [Line Items]
Sales	51.4	82.6
James Allen
Disaggregation of Revenue [Line Items]
Sales	43.8	52.0
Peoples
Disaggregation of Revenue [Line Items]
Sales	24.7	42.6
International segment
Disaggregation of Revenue [Line Items]
Sales	64.9	111.5
Other
Disaggregation of Revenue [Line Items]
Sales	6.1	19.9
E-commerce
Disaggregation of Revenue [Line Items]
Sales	164.7	154.3
Other
Disaggregation of Revenue [Line Items]
Sales	6.1	19.9
North America
Disaggregation of Revenue [Line Items]
Sales	781.1	1,300.3
North America | Bridal
Disaggregation of Revenue [Line Items]
Sales	314.1	594.7
North America | Fashion
Disaggregation of Revenue [Line Items]
Sales	297.9	467.4
North America | Watches
Disaggregation of Revenue [Line Items]
Sales	24.6	48.2
North America | Other
Disaggregation of Revenue [Line Items]
Sales	144.5	190.0
North America | Store
Disaggregation of Revenue [Line Items]
Sales	631.9	1,157.3
North America | Kay
Disaggregation of Revenue [Line Items]
Sales	333.5	579.3
North America | Zales
Disaggregation of Revenue [Line Items]
Sales	182.3	288.8
North America | Jared
Disaggregation of Revenue [Line Items]
Sales	145.4	255.0
North America | Piercing Pagoda
Disaggregation of Revenue [Line Items]
Sales	51.4	82.6
North America | James Allen
Disaggregation of Revenue [Line Items]
Sales	43.8	52.0
North America | Peoples
Disaggregation of Revenue [Line Items]
Sales	24.7	42.6
North America | International segment
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
North America | Other
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
North America | E-commerce
Disaggregation of Revenue [Line Items]
Sales	149.2	143.0
North America | Other
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
International segment
Disaggregation of Revenue [Line Items]
Sales	64.9	111.5
International segment | Bridal
Disaggregation of Revenue [Line Items]
Sales	28.1	48.6
International segment | Fashion
Disaggregation of Revenue [Line Items]
Sales	12.6	22.4
International segment | Watches
Disaggregation of Revenue [Line Items]
Sales	17.5	34.0
International segment | Other
Disaggregation of Revenue [Line Items]
Sales	6.7	6.5
International segment | Store
Disaggregation of Revenue [Line Items]
Sales	49.4	100.2
International segment | Kay
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
International segment | Zales
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
International segment | Jared
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
International segment | Piercing Pagoda
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
International segment | James Allen
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
International segment | Peoples
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
International segment | International segment
Disaggregation of Revenue [Line Items]
Sales	64.9	111.5
International segment | Other
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
International segment | E-commerce
Disaggregation of Revenue [Line Items]
Sales	15.5	11.3
International segment | Other
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
Other
Disaggregation of Revenue [Line Items]
Sales	6.1	19.9
Other | Bridal
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
Other | Fashion
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
Other | Watches
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
Other | Other
Disaggregation of Revenue [Line Items]
Sales	6.1	19.9
Other | Store
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
Other | Kay
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
Other | Zales
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
Other | Jared
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
Other | Piercing Pagoda
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
Other | James Allen
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
Other | Peoples
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
Other | International segment
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
Other | Other
Disaggregation of Revenue [Line Items]
Sales	6.1	19.9
Other | E-commerce
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
Other | Other
Disaggregation of Revenue [Line Items]
Sales	$ 6.1	$ 19.9