Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
Allowance for doubtful accounts
Changes in valuation and qualifying accounts
Balance at Beginning of Period	$ 1,149	$ 1,808	$ 1,850
Additions	1,541	326	998
Deductions	(336)	(977)	(1,056)
Translation Adjustments	(32)	(8)	16
Balance at End of Period	2,322	1,149	1,808
Reserve for excess and obsolete inventory
Changes in valuation and qualifying accounts
Balance at Beginning of Period	8,599	8,853	5,390
Additions	2,937	1,719	5,016
Deductions	(1,218)	(1,862)	(1,580)
Translation Adjustments	(203)	(111)	27
Balance at End of Period	10,115	8,599	8,853
Deferred tax asset valuation allowance
Changes in valuation and qualifying accounts
Balance at Beginning of Period	6,358	2,984	2,334
Additions	1,086	3,538	615
Deductions	(1,891)	(119)	0
Translation Adjustments	148	(45)	35
Balance at End of Period	$ 5,701	$ 6,358	$ 2,984