Fair value measurement - Fair Value of Assets and Liabilities (Details) - USD ($) $ in Millions	May 01, 2021	Jan. 30, 2021	May 02, 2020
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 5.1	$ 5.7	$ 7.4
Liabilities	0.0	0.0	0.0
Level 1 | US Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	5.1	5.7	7.4
Level 1 | Foreign currency contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0.0	0.0	0.0
Liabilities	0.0	0.0	0.0
Level 1 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	0.0	0.0	0.0
Level 1 | US government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0.0	0.0	0.0
Level 1 | Corporate bonds and notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0.0	0.0	0.0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	9.5	9.8	12.1
Liabilities	(0.8)	(0.4)	(0.3)
Level 2 | US Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0.0	0.0	0.0
Level 2 | Foreign currency contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0.2	0.1	0.1
Liabilities	(0.8)	(0.3)	(0.3)
Level 2 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	0.0	(0.1)	0.0
Level 2 | US government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	3.1	3.2	4.0
Level 2 | Corporate bonds and notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	6.2	6.5	8.0
Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	14.6	15.5	19.5
Liabilities	(0.8)	(0.4)	(0.3)
Carrying Value | US Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	5.1	5.7	7.4
Carrying Value | Foreign currency contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0.2	0.1	0.1
Liabilities	(0.8)	(0.3)	(0.3)
Carrying Value | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	0.0	(0.1)	0.0
Carrying Value | US government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	3.1	3.2	4.0
Carrying Value | Corporate bonds and notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 6.2	$ 6.5	$ 8.0