Income taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Feb. 01, 2020	Feb. 02, 2019	Feb. 03, 2018	Jan. 28, 2017
Operating Loss Carryforwards [Line Items]
Statutory tax rate (percent)	21.00%	21.00%	35.00%
Deferred tax assets		$ 21.0
Capital loss carryforwards	$ 12.9	13.9
Decrease in valuation allowance	0.5
Unrecognized tax benefits	23.5	18.1	$ 12.0	$ 12.0
Accrued interest related to unrecognized tax benefits	3.9
Accrued penalties	0.7
Increase resulting from settlements with taxing authorities	25.5
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards	109.2
Capital loss carryforwards	3.0
Internal Revenue Service (IRS)
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards	15.1
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards	14.1
Deferred tax assets	13.7
Foreign capital loss carry forward	$ 10.5	$ 11.6
Bermuda
Operating Loss Carryforwards [Line Items]
Statutory tax rate (percent)	0.00%