Annual report pursuant to Section 13 and 15(d)

Income taxes (Details)

v3.5.0.2
Income taxes (Details) - USD ($)
$ in Thousands
 12 Months Ended
Jul. 31, 2016
Jul. 31, 2015
Income taxes (Details) [Line Items]    
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount $ 14,700 $ 200
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration 55,000  
Deferred Tax Assets Research and Development and Other Tax Credit Carryforwards 2,152 $ 1,134
Foreign Loss Carryforwards 7,900  
Undistributed Earnings of Foreign Subsidiaries 101  
Liability for Uncertain Tax Position 0  
U.S. Federal Tax [Member]    
Income taxes (Details) [Line Items]    
Deferred Tax Assets Research and Development and Other Tax Credit Carryforwards $ 1,000  
Minimum [Member] | Domestic Tax Authority [Member]    
Income taxes (Details) [Line Items]    
Operating Loss Carryforwards Expiration Year 2030  
Minimum [Member] | Research Tax Credit Carryforward [Member]    
Income taxes (Details) [Line Items]    
Tax Credit Carryforward Expiration Year 2025  
Maximum [Member] | Domestic Tax Authority [Member]    
Income taxes (Details) [Line Items]    
Operating Loss Carryforwards Expiration Year 2035  
Maximum [Member] | Research Tax Credit Carryforward [Member]    
Income taxes (Details) [Line Items]    
Tax Credit Carryforward Expiration Year 2036