Restructuring Plans - Restructuring and Related Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		33 Months Ended
	Oct. 31, 2020	Nov. 02, 2019	Oct. 31, 2020	Nov. 02, 2019	Oct. 31, 2020
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 3.6	$ 9.2	$ 45.2	$ 59.4
Cost of sales
Restructuring Cost and Reserve [Line Items]
Inventory charges	2.0	1.4	1.4	5.8
Restructuring Charges
Restructuring Cost and Reserve [Line Items]
Restructuring charges	3.6	9.2	45.2	59.4
Signet Path to Brillance
Restructuring Cost and Reserve [Line Items]
Restructuring charges	5.6	$ 10.6	46.6	$ 65.2	$ 251.6
Inventory charges | Signet Path to Brillance
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2.0		1.4		72.8
Termination benefits | Signet Path to Brillance
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2.3		25.4		51.2
Store closure and other costs | Signet Path to Brillance
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 1.3		$ 19.8		$ 127.6