Retirement plans - Fair Value of Unfunded, Non-qualified Deferred Compensation Plans Assets (Details) - USD ($) $ in Millions	Jan. 29, 2022	Jan. 30, 2021
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, plan assets, amount	$ 22.7	$ 21.7
Mutual funds
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, plan assets, amount	12.4	5.0
Level 1
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, plan assets, amount	12.4	5.0
Level 1 | Mutual funds
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, plan assets, amount	12.4	5.0
NAV | Money market mutual funds
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, plan assets, amount	$ 10.3	$ 16.7