Annual report pursuant to Section 13 and 15(d)

Summary of significant accounting policies (Details)

v3.20.2
Summary of significant accounting policies (Details)
12 Months Ended
Jul. 31, 2020
USD ($)
shares
Jul. 31, 2019
USD ($)
shares
Jul. 31, 2018
USD ($)
shares
Aug. 01, 2019
USD ($)
Summary of significant accounting policies (Details) [Line Items]        
Number of operating segments 3      
Cash and cash equivalents $ 47,865,000 $ 60,146,000 $ 60,041,000  
Contractual adjustment percentage 88.00% 88.00% 85.00%  
Finite-lived intangible asset, useful life 5 years      
Goodwill impairment $ 0 $ 0 $ 0  
Advertising expense 437,000 $ 374,000 580,000  
Incremental common shares attributable to dilutive effect of share-based payment arrangements (in Shares) | shares   125,000    
Share-based compensation expenses 933,000 $ 939,000 813,000  
Employee Benefits and Share-based Compensation 10      
Share-based payment arrangement, nonvested award, option, cost not yet recognized, amount $ 861,000      
Share-based payment arrangement, nonvested award, cost not yet recognized, period for recognition 14 months      
Right-of-use assets $ 19,916,000   $ 24,400,000
Operating lease liabilities 20,800,000     $ 25,100,000
Deferred rent credit, current 700,000      
Impairment of long-lived assets $ 0 $ 0 $ 0  
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      
Patents [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Finite-lived intangible asset, useful life 10 years      
Clinical Services [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Concentration Risk, Percentage 63.00% 63.00% 71.00%  
Clinical Laboratory Services [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Receivable percentage 68.00% 63.00%    
Third Party Payer And Health Maintenance Organizations [Member] | Clinical Services [Member] | Revenue Benchmark [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Concentration Risk, Percentage 24.00% 36.00% 39.00%  
Third Party Payer And Health Maintenance Organizations [Member] | Clinical Services [Member] | Revenue Benchmark [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Concentration Risk, Percentage 16.00%      
Foreign Bank [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Cash and cash equivalents $ 900,000 $ 700,000    
Restricted Stock Units (RSUs) [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Share-based compensation expenses $ 923,000 $ 939,000 $ 813,000  
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      
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) (in Shares) | shares 40,000   624,000  
Outstanding options [Member]        
Summary of significant accounting policies (Details) [Line Items]        
Antidilutive securities excluded from computation of earnings per share, amount (in shares) (in Shares) | shares 1,904,000 1,324,000 291,000