Revenue recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	May 05, 2018	Apr. 29, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 1,480.6	$ 1,403.4
North America
Disaggregation of Revenue [Line Items]
Revenue	1,347.8	1,274.4
International
Disaggregation of Revenue [Line Items]
Revenue	128.7	122.5
Other
Disaggregation of Revenue [Line Items]
Revenue	4.1	6.5
Bridal
Disaggregation of Revenue [Line Items]
Revenue	673.5	616.0
Bridal | North America
Disaggregation of Revenue [Line Items]
Revenue	617.9	562.9
Bridal | International
Disaggregation of Revenue [Line Items]
Revenue	55.6	53.1
Bridal | Other
Disaggregation of Revenue [Line Items]
Revenue	0.0	0.0
Fashion
Disaggregation of Revenue [Line Items]
Revenue	487.0	476.7
Fashion | North America
Disaggregation of Revenue [Line Items]
Revenue	461.1	450.9
Fashion | International
Disaggregation of Revenue [Line Items]
Revenue	25.9	25.8
Fashion | Other
Disaggregation of Revenue [Line Items]
Revenue	0.0	0.0
Watches
Disaggregation of Revenue [Line Items]
Revenue	91.3	88.0
Watches | North America
Disaggregation of Revenue [Line Items]
Revenue	52.2	51.5
Watches | International
Disaggregation of Revenue [Line Items]
Revenue	39.1	36.5
Watches | Other
Disaggregation of Revenue [Line Items]
Revenue	0.0	0.0
Other
Disaggregation of Revenue [Line Items]
Revenue	228.8	222.7
Other | North America
Disaggregation of Revenue [Line Items]
Revenue	216.6	209.1
Other | International
Disaggregation of Revenue [Line Items]
Revenue	8.1	7.1
Other | Other
Disaggregation of Revenue [Line Items]
Revenue	4.1	6.5
Store
Disaggregation of Revenue [Line Items]
Revenue	1,334.1	1,322.4
Store | North America
Disaggregation of Revenue [Line Items]
Revenue	1,213.7	1,203.3
Store | International
Disaggregation of Revenue [Line Items]
Revenue	116.3	112.6
Store | Other
Disaggregation of Revenue [Line Items]
Revenue	4.1	6.5
E-commerce
Disaggregation of Revenue [Line Items]
Revenue	146.5	81.0
E-commerce | North America
Disaggregation of Revenue [Line Items]
Revenue	134.1	71.1
E-commerce | International
Disaggregation of Revenue [Line Items]
Revenue	12.4	9.9
E-commerce | Other
Disaggregation of Revenue [Line Items]
Revenue	0.0	$ 0.0
James Allen | E-commerce | North America
Disaggregation of Revenue [Line Items]
Revenue	$ 53.3