Revenue recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Feb. 01, 2020	Nov. 02, 2019	Aug. 03, 2019	May 04, 2019	Feb. 02, 2019	Nov. 03, 2018	Aug. 04, 2018	May 05, 2018	Feb. 01, 2020	Feb. 02, 2019	Feb. 03, 2018
Disaggregation of Revenue [Line Items]
Total sales	$ 2,153.3	$ 1,187.7	$ 1,364.4	$ 1,431.7	$ 2,154.7	$ 1,191.7	$ 1,420.1	$ 1,480.6	$ 6,137.1	$ 6,247.1	$ 6,253.0
Store
Disaggregation of Revenue [Line Items]
Total sales									5,333.4	5,535.8	5,734.2
Kay
Disaggregation of Revenue [Line Items]
Total sales									2,397.7	2,417.8	2,428.1
Zales
Disaggregation of Revenue [Line Items]
Total sales									1,261.3	1,260.7	1,244.3
Jared
Disaggregation of Revenue [Line Items]
Total sales									1,088.1	1,141.4	1,192.1
Piercing Pagoda
Disaggregation of Revenue [Line Items]
Total sales									331.7	302.5	278.5
James Allen
Disaggregation of Revenue [Line Items]
Total sales									250.6	223.7	88.1
Peoples
Disaggregation of Revenue [Line Items]
Total sales									200.6	208.5	215.4
Regional banners
Disaggregation of Revenue [Line Items]
Total sales									35.8	87.1	168.7
International
Disaggregation of Revenue [Line Items]
Total sales									518.0	576.5	616.7
Other
Disaggregation of Revenue [Line Items]
Total sales									53.3	28.9	21.1
eCommerce
Disaggregation of Revenue [Line Items]
Total sales									750.4	682.4	497.7
Other
Disaggregation of Revenue [Line Items]
Total sales									53.3	28.9	21.1
Bridal
Disaggregation of Revenue [Line Items]
Total sales									2,617.7	2,712.6	2,654.6
Fashion
Disaggregation of Revenue [Line Items]
Total sales									2,241.5	2,254.4	2,305.2
Watches
Disaggregation of Revenue [Line Items]
Total sales									384.0	429.1	439.1
Other
Disaggregation of Revenue [Line Items]
Total sales									893.9	851.0	854.1
North America
Disaggregation of Revenue [Line Items]
Total sales									5,565.8	5,641.7	5,615.2
North America | Store
Disaggregation of Revenue [Line Items]
Total sales									4,880.2	5,022.4	5,176.7
North America | Kay
Disaggregation of Revenue [Line Items]
Total sales									2,397.7	2,417.8	2,428.1
North America | Zales
Disaggregation of Revenue [Line Items]
Total sales									1,261.3	1,260.7	1,244.3
North America | Jared
Disaggregation of Revenue [Line Items]
Total sales									1,088.1	1,141.4	1,192.1
North America | Piercing Pagoda
Disaggregation of Revenue [Line Items]
Total sales									331.7	302.5	278.5
North America | James Allen
Disaggregation of Revenue [Line Items]
Total sales									250.6	223.7	88.1
North America | Peoples
Disaggregation of Revenue [Line Items]
Total sales									200.6	208.5	215.4
North America | Regional banners
Disaggregation of Revenue [Line Items]
Total sales									35.8	87.1	168.7
North America | International
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
North America | Other
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
North America | eCommerce
Disaggregation of Revenue [Line Items]
Total sales									685.6	619.3	438.5
North America | Other
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
North America | Bridal
Disaggregation of Revenue [Line Items]
Total sales									2,403.4	2,478.6	2,407.3
North America | Fashion
Disaggregation of Revenue [Line Items]
Total sales									2,131.0	2,128.1	2,168.2
North America | Watches
Disaggregation of Revenue [Line Items]
Total sales									214.9	238.2	243.6
North America | Other
Disaggregation of Revenue [Line Items]
Total sales									816.5	796.8	796.1
International
Disaggregation of Revenue [Line Items]
Total sales									518.0	576.5	616.7
International | Store
Disaggregation of Revenue [Line Items]
Total sales									453.2	513.4	557.5
International | Kay
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
International | Zales
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
International | Jared
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
International | Piercing Pagoda
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
International | James Allen
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
International | Peoples
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
International | Regional banners
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
International | International
Disaggregation of Revenue [Line Items]
Total sales									518.0	576.5	616.7
International | Other
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
International | eCommerce
Disaggregation of Revenue [Line Items]
Total sales									64.8	63.1	59.2
International | Other
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
International | Bridal
Disaggregation of Revenue [Line Items]
Total sales									214.3	234.0	247.3
International | Fashion
Disaggregation of Revenue [Line Items]
Total sales									110.5	126.3	137.0
International | Watches
Disaggregation of Revenue [Line Items]
Total sales									169.1	190.9	195.5
International | Other
Disaggregation of Revenue [Line Items]
Total sales									24.1	25.3	36.9
Other
Disaggregation of Revenue [Line Items]
Total sales									53.3	28.9	21.1
Other | Store
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
Other | Kay
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
Other | Zales
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
Other | Jared
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
Other | Piercing Pagoda
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
Other | James Allen
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
Other | Peoples
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
Other | Regional banners
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
Other | International
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
Other | Other
Disaggregation of Revenue [Line Items]
Total sales									53.3	28.9	21.1
Other | eCommerce
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
Other | Other
Disaggregation of Revenue [Line Items]
Total sales									53.3	28.9	21.1
Other | Bridal
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
Other | Fashion
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
Other | Watches
Disaggregation of Revenue [Line Items]
Total sales									0.0	0.0	0.0
Other | Other
Disaggregation of Revenue [Line Items]
Total sales									$ 53.3	$ 28.9	$ 21.1