Schedule II Valuation of Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balances at beginning of period	$ 3,585	$ 3,069	$ 5,093
Additions — Charged to expense	1,904	1,954	779
Reclassified to continuing operations	0	0	31
Deductions - written off	(345)	(1,438)	(2,834)
Balances at end of period	5,144	3,585	3,069
Inventory Valuation Reserve [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balances at beginning of period	13,269	12,259	11,317
Additions — Charged to expense	4,950	3,017	3,100
Reclassified to continuing operations	0	0	461
Deductions - written off	(3,136)	(2,007)	(2,619)
Balances at end of period	15,083	13,269	12,259
Valuation Allowance of Deferred Tax Assets [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balances at beginning of period	39,922	37,409	37,142
Additions — Charged to expense	2,614	8,111	10,182
Deductions - written off	(4,544)	(5,598)	(9,915)
Balances at end of period	$ 37,992	$ 39,922	$ 37,409