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