Restructuring plans - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended			48 Months Ended
	May 05, 2018	Jan. 29, 2022	Jan. 30, 2021	Feb. 01, 2020	Jan. 29, 2022	Feb. 02, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ (3.3)	$ 46.2	$ 69.9
Signet Path to Brillance
Restructuring Cost and Reserve [Line Items]
Restructuring plan, length	3 years
Restructuring charges		(3.3)	47.6	79.1	$ 249.3
Restructuring reserve		4.0	$ 10.2	$ 12.4	4.0	$ 12.6
Accrued Expenses And Other Current Liabilities | Signet Path to Brillance
Restructuring Cost and Reserve [Line Items]
Restructuring reserve		1.9			1.9
Other Noncurrent Liabilities | Signet Path to Brillance
Restructuring Cost and Reserve [Line Items]
Restructuring reserve		$ 2.1			$ 2.1