Annual report pursuant to Section 13 and 15(d)

Summary of significant accounting policies (Details) - Segment's net revenues and revenue percentages

v3.10.0.1
Summary of significant accounting policies (Details) - Segment's net revenues and revenue percentages - USD ($)
$ in Thousands
12 Months Ended
Jul. 31, 2018
Jul. 31, 2017
Jul. 31, 2016
Summary of significant accounting policies (Details) - Segment's net revenues and revenue percentages [Line Items]      
Revenue Services Net $ 104,713 $ 107,804 $ 102,773
Clinical Labs [Member]      
Summary of significant accounting policies (Details) - Segment's net revenues and revenue percentages [Line Items]      
Revenue Services Net 74,777 77,407 70,915
Service [Member] | Clinical Labs [Member]      
Summary of significant accounting policies (Details) - Segment's net revenues and revenue percentages [Line Items]      
Revenue Services Net $ 74,777 $ 77,407 $ 70,915
Revenue Services Net Percentage 100.00% 100.00% 100.00%
Service [Member] | Clinical Labs [Member] | Third-Party Payor [Member]      
Summary of significant accounting policies (Details) - Segment's net revenues and revenue percentages [Line Items]      
Revenue Services Net $ 41,370 $ 43,059 $ 34,454
Revenue Services Net Percentage 56.00% 56.00% 49.00%
Service [Member] | Clinical Labs [Member] | Medicare [Member]      
Summary of significant accounting policies (Details) - Segment's net revenues and revenue percentages [Line Items]      
Revenue Services Net $ 12,111 $ 12,705 $ 11,392
Revenue Services Net Percentage 16.00% 16.00% 16.00%
Service [Member] | Clinical Labs [Member] | Health Maintenance Organizations [Member]      
Summary of significant accounting policies (Details) - Segment's net revenues and revenue percentages [Line Items]      
Revenue Services Net $ 11,359 $ 10,263 $ 10,325
Revenue Services Net Percentage 15.00% 13.00% 14.00%
Service [Member] | Clinical Labs [Member] | Self-Pay [Member]      
Summary of significant accounting policies (Details) - Segment's net revenues and revenue percentages [Line Items]      
Revenue Services Net $ 9,937 $ 11,380 $ 14,744
Revenue Services Net Percentage 13.00% 15.00% 21.00%