Annual report pursuant to Section 13 and 15(d)

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

v3.7.0.1
Summary of significant accounting policies (Details) - Segment's net revenues and revenue percentages - USD ($)
$ in Thousands
 12 Months Ended
Jul. 31, 2017
Jul. 31, 2016
Jul. 31, 2015
Summary of significant accounting policies (Details) - Segment's net revenues and revenue percentages [Line Items]      
Sales Revenue Services Net $ 77,407 $ 70,915 $ 63,414
Clinical Labs [Member]      
Summary of significant accounting policies (Details) - Segment's net revenues and revenue percentages [Line Items]      
Sales Revenue Services Net $ 77,407 $ 70,915 $ 63,414
Sales Revenue Services Net Percentage 100.00% 100.00% 100.00%
Clinical Labs [Member] | Third-Party Payor [Member]      
Summary of significant accounting policies (Details) - Segment's net revenues and revenue percentages [Line Items]      
Sales Revenue Services Net $ 43,059 $ 34,454 $ 30,685
Sales Revenue Services Net Percentage 56.00% 49.00% 49.00%
Clinical Labs [Member] | Self-Pay [Member]      
Summary of significant accounting policies (Details) - Segment's net revenues and revenue percentages [Line Items]      
Sales Revenue Services Net $ 11,380 $ 14,744 $ 11,028
Sales Revenue Services Net Percentage 15.00% 21.00% 17.00%
Clinical Labs [Member] | Medicare [Member]      
Summary of significant accounting policies (Details) - Segment's net revenues and revenue percentages [Line Items]      
Sales Revenue Services Net $ 12,705 $ 11,392 $ 11,981
Sales Revenue Services Net Percentage 16.00% 16.00% 19.00%
Clinical Labs [Member] | Health Maintenance Organizations [Member]      
Summary of significant accounting policies (Details) - Segment's net revenues and revenue percentages [Line Items]      
Sales Revenue Services Net $ 10,263 $ 10,325 $ 9,720
Sales Revenue Services Net Percentage 13.00% 14.00% 15.00%