Retirement plans - Change in UK Plan Assets (Details) - Pension plan - Foreign Plan - USD ($) $ in Millions	12 Months Ended
	Jan. 30, 2021	Feb. 01, 2020
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value at beginning of year	$ 281.9	$ 245.5
Actual return on UK Plan assets	11.9	36.8
Employer contributions	4.4	5.3
Members’ contributions	0.0	0.2
Benefits paid	(9.8)	(9.4)
Foreign currency translation	10.8	3.5
Fair value at end of year	$ 299.2	$ 281.9