Annual report pursuant to Section 13 and 15(d)

Income taxes (Details)

v3.10.0.1
Income taxes (Details) - USD ($)
 5 Months Ended 7 Months Ended 12 Months Ended
Jul. 31, 2018
Dec. 31, 2017
Jul. 31, 2018
Jul. 31, 2018
Jul. 31, 2017
Jul. 31, 2016
Income taxes (Details) [Line Items]            
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent   35.00% 21.00% 26.40% 34.00% (34.00%)
Effective Income Tax Rate Reconciliation, Tax Credit, Amount $ 1,100,000     $ 1,100,000    
Tax Cut and Job Act 2017 Deferred Tax Assets Valuation Allowance       11,500,000    
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount       8,100,000 $ 2,300,000  
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration 65,800,000   $ 65,800,000 65,800,000    
Deferred Tax Assets Research and Development and Other Tax Credit Carryforwards 1,286   1,286 1,286 $ 2,208  
Deferred Tax Assets, Operating Loss Carryforwards 6,500,000   6,500,000 6,500,000    
Foreign Loss Carryforwards 10,800,000   10,800,000 10,800,000    
Liability for Uncertain Tax Position 0   0 $ 0    
Maximum [Member]            
Income taxes (Details) [Line Items]            
Operating Loss Carryforward Expiration Year End       2038    
Minimum [Member]            
Income taxes (Details) [Line Items]            
Operating Loss Carryforward Expiration Year Begining       2037    
Domestic Tax Authority [Member] | Maximum [Member]            
Income taxes (Details) [Line Items]            
Operating Loss Carryforwards Expiration Year       2038    
Domestic Tax Authority [Member] | Minimum [Member]            
Income taxes (Details) [Line Items]            
Operating Loss Carryforwards Expiration Year       2030    
Research Tax Credit Carryforward [Member] | Maximum [Member]            
Income taxes (Details) [Line Items]            
Tax Credit Carryforward Expiration Year       2038    
Research Tax Credit Carryforward [Member] | Minimum [Member]            
Income taxes (Details) [Line Items]            
Tax Credit Carryforward Expiration Year       2025    
U.S. Federal Tax [Member]            
Income taxes (Details) [Line Items]            
Deferred Tax Assets Research and Development and Other Tax Credit Carryforwards $ 1,300,000   $ 1,300,000 $ 1,300,000