Accounts receivable, net - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Oct. 31, 2015	Jan. 31, 2015	Nov. 01, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage allowance on leases	100.00%
Loan allowance maturity period	90 days
Finance receivable age	90 days
Other Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	$ 9.9	$ 13.7	$ 9.5
Valuation of allowance	$ 0.6	$ 0.5	$ 0.3