Annual report pursuant to Section 13 and 15(d)

Summary of significant accounting policies (Details)

v3.5.0.2
Summary of significant accounting policies (Details)
$ in Thousands
 12 Months Ended
Jul. 31, 2016
USD ($)
shares
Jul. 31, 2015
USD ($)
shares
Jul. 31, 2014
USD ($)
shares
Jul. 31, 2013
USD ($)
Summary of significant accounting policies (Details) [Line Items]        
Number of Operating Segments 3      
Cash and Cash Equivalents, at Carrying Value $ 67,777 $ 18,109 $ 17,455 $ 9,007
Contractual Adjustment Percentage 84.00% 85.00% 86.00%  
Minimum Collection Period for Outstanding Accounts Receivable 210 days 210 days    
Percentage Of Account Receivable Over Specified Days 100.00% 100.00%    
Maximum Period for Allowance for Doubtful Accounts 210 days 210 days    
Percentage of Doubtful Accounts to Accounts Receivable 19.40% 12.90%    
Finite-Lived Intangible Asset, Useful Life 10 years      
Impairment of Long-Lived Assets Held-for-use $ 0 $ 0 $ 0  
Advertising Expense $ 601 556 440  
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in Shares) | shares 449,000      
Share-based Compensation $ 525 429 594  
Excess Tax Benefit from Share-based Compensation, Operating Activities 0 $ 0 $ 0  
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options $ 810      
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition 16 months      
Outstanding Options [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in Shares) | shares 282,000 977,000 182,000  
Foreign Bank [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Cash and Cash Equivalents, at Carrying Value $ 500 $ 500    
Clinical Labs [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Sales Revenue Services Net Percentage 100.00% 100.00% 100.00%  
Receivable Percentage 71.00% 68.00%    
Life Sciences [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Royalties Receivable $ 500 $ 100    
Minimum [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Finite-Lived Intangible Asset, Useful Life 4 years      
Minimum [Member] | Building and Building Improvements [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Property, Plant and Equipment, Estimated Useful Lives 15      
Minimum [Member] | Machinery and Equipment [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Property, Plant and Equipment, Estimated Useful Lives 3      
Maximum [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Finite-Lived Intangible Asset, Useful Life 15 years      
Maximum [Member] | Building and Building Improvements [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Property, Plant and Equipment, Estimated Useful Lives 30      
Maximum [Member] | Machinery and Equipment [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Property, Plant and Equipment, Estimated Useful Lives 10      
In the Money Stock Options [Member] | Unvested Restricted Stock [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in Shares) | shares   403,000 1,016,000  
United Health Care of New York [Member] | Clinical Labs [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Sales Revenue Services Net Percentage 30.00% 28.00% 25.00%