Revenue from Contracts with Customers - Contract Assets And Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended
	Oct. 31, 2018	Jan. 31, 2019	Jan. 31, 2018
Contract Assets:
Unbilled revenue-current		$ 340	$ 0
Unbilled revenue - non-current		0	0
Total unbilled revenue		340	0
Contract Liabilities:
Deferred revenue & customer deposits - current		556	0
Deferred revenue & customer deposits - non-current		11	0
Total deferred revenue & customer deposits		$ 567	$ 0
Minimum
Contract With Customers [Line Items]
Contract with customers, turn over period	3 months
Maximum
Contract With Customers [Line Items]
Contract with customers, turn over period	6 months