Revenue recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	2 Months Ended	3 Months Ended		9 Months Ended
	Nov. 03, 2018	Nov. 03, 2018	Oct. 28, 2017	Nov. 03, 2018	Oct. 28, 2017
Disaggregation of Revenue [Line Items]
Revenue		$ 1,191.7	$ 1,156.9	$ 4,092.4	$ 3,959.9
North America
Disaggregation of Revenue [Line Items]
Revenue		1,064.3	1,022.3	3,698.8	3,558.9
International
Disaggregation of Revenue [Line Items]
Revenue		121.3	128.4	381.5	382.8
Other
Disaggregation of Revenue [Line Items]
Revenue		6.1	6.2	12.1	18.2
Bridal
Disaggregation of Revenue [Line Items]
Revenue		566.5	556.7	1,889.5	1,779.7
Bridal | North America
Disaggregation of Revenue [Line Items]
Revenue		514.6	497.3	1,730.2	1,614.6
Bridal | International
Disaggregation of Revenue [Line Items]
Revenue		51.9	59.4	159.3	165.1
Bridal | Other
Disaggregation of Revenue [Line Items]
Revenue		0.0	0.0	0.0	0.0
Fashion
Disaggregation of Revenue [Line Items]
Revenue		356.1	338.9	1,300.1	1,284.7
Fashion | North America
Disaggregation of Revenue [Line Items]
Revenue		332.5	319.1	1,223.4	1,209.9
Fashion | International
Disaggregation of Revenue [Line Items]
Revenue		23.6	19.8	76.7	74.8
Fashion | Other
Disaggregation of Revenue [Line Items]
Revenue		0.0	0.0	0.0	0.0
Watches
Disaggregation of Revenue [Line Items]
Revenue		86.9	86.1	283.8	276.8
Watches | North America
Disaggregation of Revenue [Line Items]
Revenue		45.7	44.9	156.7	155.1
Watches | International
Disaggregation of Revenue [Line Items]
Revenue		41.2	41.2	127.1	121.7
Watches | Other
Disaggregation of Revenue [Line Items]
Revenue		0.0	0.0	0.0	0.0
Other
Disaggregation of Revenue [Line Items]
Revenue		182.2	175.2	619.0	618.7
Other | North America
Disaggregation of Revenue [Line Items]
Revenue		171.5	161.0	588.5	579.3
Other | International
Disaggregation of Revenue [Line Items]
Revenue		4.6	8.0	18.4	21.2
Other | Other
Disaggregation of Revenue [Line Items]
Revenue		6.1	6.2	12.1	18.2
Store
Disaggregation of Revenue [Line Items]
Revenue		1,060.6	1,070.0	3,658.5	3,697.8
Store | North America
Disaggregation of Revenue [Line Items]
Revenue		952.1	952.7	3,316.0	3,347.5
Store | International
Disaggregation of Revenue [Line Items]
Revenue		108.5	117.3	342.5	350.3
Store | Other
Disaggregation of Revenue [Line Items]
Revenue		0.0	0.0	0.0	0.0
E-commerce
Disaggregation of Revenue [Line Items]
Revenue		125.0	80.7	421.8	243.9
E-commerce | North America
Disaggregation of Revenue [Line Items]
Revenue		112.2	69.6	382.8	211.4
E-commerce | International
Disaggregation of Revenue [Line Items]
Revenue		12.8	11.1	39.0	32.5
E-commerce | Other
Disaggregation of Revenue [Line Items]
Revenue		0.0	0.0	0.0	0.0
Other
Disaggregation of Revenue [Line Items]
Revenue		6.1	6.2	12.1	18.2
Other | North America
Disaggregation of Revenue [Line Items]
Revenue		0.0	0.0	0.0	0.0
Other | International
Disaggregation of Revenue [Line Items]
Revenue		0.0	0.0	0.0	0.0
Other | Other
Disaggregation of Revenue [Line Items]
Revenue		6.1	$ 6.2	12.1	$ 18.2
James Allen | E-commerce | North America
Disaggregation of Revenue [Line Items]
Revenue	$ 23.7	$ 52.5		$ 160.2