Schedule II Valuation of Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2011
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ 5,093	$ 6,005	$ 6,183
Additions — Charged to expense	1,018	1,593	1,287
Due to acquired businesses	531	159	52
Deductions - written off	(1,429)	(1,930)	(2,293)
Deductions	(1,032)	0	0
Ending balance	6,005	6,183	7,137
Inventory Valuation Reserve [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	11,317	11,316	13,009
Additions — Charged to expense	2,629	2,200	3,750
Due to acquired businesses	2,887	445	632
Deductions - written off	1,811	4,338	7,317
Deductions	(3,704)	0	0
Ending balance	11,316	13,009	15,944
Valuation Allowance of Deferred Tax Assets [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	37,142	25,847	31,844
Additions — Charged to expense	10,853	2,579	5,933
Due to acquired businesses	983	0	0
Deductions - written off	541	3,226	1,523
Deductions	0	(5,350)	(76)
Ending balance	$ 25,847	$ 31,844	$ 27,510