Annual report pursuant to Section 13 and 15(d)

Summary of significant accounting policies (Details)

v3.7.0.1
Summary of significant accounting policies (Details)
$ in Thousands
 12 Months Ended
Jul. 31, 2017
USD ($)
shares
Jul. 31, 2016
USD ($)
shares
Jul. 31, 2015
USD ($)
shares
Jul. 31, 2014
USD ($)
Summary of significant accounting policies (Details) [Line Items]        
Number of Operating Segments 3      
Cash and Cash Equivalents, at Carrying Value $ 64,167 $ 67,777 $ 18,109 $ 17,455
Contractual Adjustment Percentage 84.00% 84.00% 85.00%  
Percentage of Doubtful Accounts to Accounts Receivable 19.10% 19.40%    
Finite-Lived Intangible Asset, Useful Life 10 years      
Impairment of Long-Lived Assets Held-for-use $ 0 $ 0 $ 0  
Advertising Expense 649 $ 601 556  
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in Shares) | shares   449,000    
Share-based Compensation 831 $ 525 429  
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 $ 1,187      
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition 17 months      
Clinical Labs [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Sales Revenue Services Net Percentage 100.00% 100.00% 100.00%  
Receivable Percentage 75.00% 71.00%    
Life Sciences [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Royalties Receivable $ 400 $ 500    
Minimum [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Finite-Lived Intangible Asset, Useful Life 4 years      
Maximum [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Finite-Lived Intangible Asset, Useful Life 15 years      
United Health Care of New York [Member] | Clinical Labs [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Sales Revenue Services Net Percentage 39.00% 30.00% 28.00%  
Unvested Restricted Stock [Member] | In the Money Stock Options [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in Shares) | shares 961,000   403,000  
Outstanding Options [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in Shares) | shares 0 282,000 977,000  
Building and Building Improvements [Member] | Minimum [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Property, Plant and Equipment, Useful Life 15 years      
Building and Building Improvements [Member] | Maximum [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Property, Plant and Equipment, Useful Life 30 years      
Machinery and Equipment [Member] | Minimum [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Property, Plant and Equipment, Useful Life 3 years      
Machinery and Equipment [Member] | Maximum [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Property, Plant and Equipment, Useful Life 10 years      
Foreign Bank [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Cash and Cash Equivalents, at Carrying Value $ 500 $ 500