Lease information Future minimum payments (Details) $ in Thousands	Jan. 31, 2018 USD ($)
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 1,884
Capital Lease Obligations, Current	323
Operating Leases, Future Minimum Payments, Due in Two Years	1,628
Capital Leases, Future Minimum Payments Due in Two Years	257
Operating Leases, Future Minimum Payments, Due in Three Years	1,536
Capital Leases, Future Minimum Payments Due in Three Years	255
Operating Leases, Future Minimum Payments, Due in Four Years	1,494
Capital Leases, Future Minimum Payments Due in Four Years	89
Operating Leases, Future Minimum Payments, Due in Five Years	1,468
Capital Leases, Future Minimum Payments Due in Five Years	22
Operating Leases, Future Minimum Payments, Due Thereafter	8,249
Capital Leases, Future Minimum Payments Due Thereafter	0
Operating Leases, Future Minimum Payments Due	16,259
Capital leases, future minimum payments, interest included in payments	946
Interest Portion of Minimum Lease Payments, Sale Leaseback Transactions	100
Capital Lease Obligations	$ 846