Significant Customers and Geographic Information - Revenues by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues	$ 44,551	$ 31,132	$ 85,688	$ 60,315
United States
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues	28,751	21,942	56,062	42,610
Foreign Countries
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues	$ 15,800	$ 9,190	$ 29,626	$ 17,705