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Restructuring Plans - Restructuring and Related Costs (Details) - USD ($) $ in Millions	3 Months Ended		27 Months Ended
	May 02, 2020	May 04, 2019	May 02, 2020
Restructuring Cost and Reserve [Line Items]
Inventory charges	$ (0.4)	$ 0.0
Restructuring charges	12.7	26.8
Signet Path to Brillance
Restructuring Cost and Reserve [Line Items]
Restructuring charges	12.3	26.8	$ 217.3
Signet Path to Brillance \| Cost of sales
Restructuring Cost and Reserve [Line Items]
Inventory charges	(0.4)	0.0
Signet Path to Brillance \| Restructuring Charges
Restructuring Cost and Reserve [Line Items]
Other Plan related expenses	12.7	$ 26.8
Inventory charges \| Signet Path to Brillance
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(0.4)		71.0
Termination benefits \| Signet Path to Brillance
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2.9		28.7
Store closure and other costs \| Signet Path to Brillance
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 9.8		$ 117.6