Retirement plans - Fair Value of Unfunded, Non-qualified Deferred Compensation Plans Assets (Details) - USD ($) $ in Millions	Jan. 30, 2021	Feb. 01, 2020
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, plan assets, amount	$ 28.0	$ 27.5
Corporate-owned life insurance plans
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, plan assets, amount	6.3	6.5
Money market funds
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, plan assets, amount	21.7	21.0
Level 1
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, plan assets, amount	21.7	21.0
Level 1 | Corporate-owned life insurance plans
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, plan assets, amount	0.0	0.0
Level 1 | Money market funds
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, plan assets, amount	21.7	21.0
Level 2
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, plan assets, amount	6.3	6.5
Level 2 | Corporate-owned life insurance plans
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, plan assets, amount	6.3	6.5
Level 2 | Money market funds
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, plan assets, amount	$ 0.0	$ 0.0