Annual report pursuant to Section 13 and 15(d)

Income taxes (Details)

v3.3.0.814
Income taxes (Details) - USD ($)
$ in Thousands
 12 Months Ended
Jul. 31, 2015
Jul. 31, 2014
Income taxes (Details) [Line Items]    
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount $ 200 $ 1,800
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration 104,100  
Deferred Tax Assets Research and Development and Other Tax Credit Carryforwards 1,134 $ 1,085
Foreign Loss Carryforwards 8,800  
Undistributed Earnings of Foreign Subsidiaries 46  
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 2018  
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 2035