Schedule II Valuation of Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balances at beginning of period	$ 4,471	$ 4,629	$ 5,144
Additions — Charged to expense	587	752	732
Deductions - written off	(53)	(910)	(1,247)
Balances at end of period	5,005	4,471	4,629
SEC Schedule, 12-09, Reserve, Inventory [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balances at beginning of period	12,582	14,322	15,083
Additions — Charged to expense	3,168	2,797	4,608
Deductions - written off	(2,346)	(4,537)	(5,369)
Balances at end of period	13,404	12,582	14,322
SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balances at beginning of period	56,866	38,563	37,992
Additions — Charged to expense	5,981	24,184	2,004
Deductions - written off	(2,774)	(5,881)	(1,433)
Balances at end of period	$ 60,073	$ 56,866	$ 38,563