Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Allowance for doubtful accounts
Changes in valuation and qualifying accounts
Balance at Beginning of Period	$ 1,808	$ 1,850	$ 2,092
Additions	326	998	15
Deductions	(977)	(1,056)	(223)
Translation Adjustments	(8)	16	(34)
Balance at End of Period	1,149	1,808	1,850
Reserve for excess and obsolete inventory
Changes in valuation and qualifying accounts
Balance at Beginning of Period	8,853	5,390	3,895
Additions	1,719	5,016	3,182
Deductions	(1,862)	(1,580)	(1,569)
Translation Adjustments	(111)	27	(118)
Balance at End of Period	8,599	8,853	5,390
Deferred tax asset valuation allowance
Changes in valuation and qualifying accounts
Balance at Beginning of Period	2,984	2,334	2,037
Additions	3,538	615	929
Deductions	(119)	0	(712)
Translation Adjustments	(45)	35	80
Balance at End of Period	$ 6,358	$ 2,984	$ 2,334