Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Allowance for doubtful accounts
Changes in valuation and qualifying accounts
Balance at Beginning of Period	$ 2,322	$ 1,149	$ 1,808
Additions	2,084	1,541	326
Deductions	(530)	(336)	(977)
Translation Adjustments	29	(32)	(8)
Balance at End of Period	3,905	2,322	1,149
Reserve for excess and obsolete inventory
Changes in valuation and qualifying accounts
Balance at Beginning of Period	10,115	8,599	8,853
Additions	9,604	2,937	1,719
Deductions	(1,623)	(1,218)	(1,862)
Translation Adjustments	183	(203)	(111)
Balance at End of Period	18,279	10,115	8,599
Deferred tax asset valuation allowance
Changes in valuation and qualifying accounts
Balance at Beginning of Period	5,701	6,358	2,984
Additions	2,597	1,086	3,538
Deductions	81	(1,891)	(119)
Translation Adjustments	(216)	148	(45)
Balance at End of Period	$ 8,163	$ 5,701	$ 6,358