Income taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Feb. 01, 2020	Feb. 02, 2019
Assets
Foreign property, plant and equipment	$ 6.5	$ 6.5
Revenue deferral	102.5	122.0
Lease liabilities	380.6	26.2
Deferred compensation	7.3	7.5
Share-based compensation	4.1	3.5
Other temporary differences	77.7	46.7
Net operating losses and foreign tax credits	137.0	151.8
Value of capital losses	12.9	13.9
Total gross deferred tax assets (liabilities)	728.6	378.1
Valuation allowance	(38.4)	(38.9)
Deferred tax assets (liabilities)	690.2	339.2
(Liabilities)
Intangible assets	(63.0)	(63.8)
US property, plant and equipment	(55.4)	(68.2)
Inventory valuation	(203.1)	(179.1)
Derivative instruments	(4.3)	(1.3)
Lease assets	(358.2)
Retirement benefit obligations	(6.7)	(5.8)
Total gross deferred tax assets (liabilities)	690.7	318.2
Total
Total gross deferred tax assets (liabilities)	37.9	59.9
Valuation allowance	(38.4)	(38.9)
Deferred tax liabilities, net	(0.5)
Deferred tax assets, net		21.0
Deferred tax assets	4.7	21.0
Non-current liabilities	$ (5.2)	$ 0.0