Fair Value Measurements - Hierarchy Levels (Details) - Recurring basis - USD ($)
$ in Thousands
Jul. 31, 2018
Jul. 31, 2017
Assets:    
Total assets $ 104 $ 102
Liabilities:    
Total liabilities 1,298 1,138
Accrued expenses:    
Liabilities:    
Assumed contingent obligation   12
Total accrued expenses   12
Other long-term liabilities:    
Liabilities:    
Contingent consideration 1,298 1,126
Total other long-term liabilities: 1,298 1,126
Money markets | Cash and cash equivalents:    
Assets:    
Money markets 104 102
Level 1    
Assets:    
Total assets 104 102
Liabilities:    
Total liabilities 0 0
Level 1 | Accrued expenses:    
Liabilities:    
Assumed contingent obligation   0
Total accrued expenses   0
Level 1 | Other long-term liabilities:    
Liabilities:    
Contingent consideration 0 0
Total other long-term liabilities: 0 0
Level 1 | Money markets | Cash and cash equivalents:    
Assets:    
Money markets 104 102
Level 2    
Assets:    
Total assets 0 0
Liabilities:    
Total liabilities 0 0
Level 2 | Accrued expenses:    
Liabilities:    
Assumed contingent obligation   0
Total accrued expenses   0
Level 2 | Other long-term liabilities:    
Liabilities:    
Contingent consideration 0 0
Total other long-term liabilities: 0 0
Level 2 | Money markets | Cash and cash equivalents:    
Assets:    
Money markets 0 0
Level 3    
Assets:    
Total assets 0 0
Liabilities:    
Total liabilities 1,298 1,138
Level 3 | Accrued expenses:    
Liabilities:    
Assumed contingent obligation   12
Total accrued expenses   12
Level 3 | Other long-term liabilities:    
Liabilities:    
Contingent consideration 1,298 1,126
Total other long-term liabilities: 1,298 1,126
Level 3 | Money markets | Cash and cash equivalents:    
Assets:    
Money markets $ 0 $ 0