Annual report pursuant to Section 13 and 15(d)

Summary of significant accounting policies (Details) - Net accounts receivable by segment

v3.10.0.1
Summary of significant accounting policies (Details) - Net accounts receivable by segment - USD ($)
$ in Thousands
Jul. 31, 2018
Jul. 31, 2017
Summary of significant accounting policies (Details) - Net accounts receivable by segment [Line Items]    
Accounts Receivable Net Current $ 13,147 $ 15,180
Clinical Labs [Member]    
Summary of significant accounting policies (Details) - Net accounts receivable by segment [Line Items]    
Accounts Receivable Net Current $ 9,771 $ 11,401
Accounts Receivable Net Current Percentage 100.00% 100.00%
Clinical Labs [Member] | Third-Party Payor [Member]    
Summary of significant accounting policies (Details) - Net accounts receivable by segment [Line Items]    
Accounts Receivable Net Current $ 4,692 $ 7,256
Accounts Receivable Net Current Percentage 48.00% 64.00%
Clinical Labs [Member] | Self-Pay [Member]    
Summary of significant accounting policies (Details) - Net accounts receivable by segment [Line Items]    
Accounts Receivable Net Current $ 2,010 $ 1,591
Accounts Receivable Net Current Percentage 20.00% 14.00%
Clinical Labs [Member] | Medicare [Member]    
Summary of significant accounting policies (Details) - Net accounts receivable by segment [Line Items]    
Accounts Receivable Net Current $ 1,740 $ 1,385
Accounts Receivable Net Current Percentage 18.00% 12.00%
Clinical Labs [Member] | Health Maintenance Organizations [Member]    
Summary of significant accounting policies (Details) - Net accounts receivable by segment [Line Items]    
Accounts Receivable Net Current $ 1,329 $ 1,169
Accounts Receivable Net Current Percentage 14.00% 10.00%
Life Sciences [Member]    
Summary of significant accounting policies (Details) - Net accounts receivable by segment [Line Items]    
Accounts Receivable Net Current $ 3,376 $ 3,779