Valuation and Qualifying Accounts (Details) (USD $) In Thousands	12 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2009
Accounts receivable - allowance for doubtful accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	$ 7,137	$ 7,931	$ 10,059
Additions - Charged to expense	1,287	2,005	1,278
Due to acquired businesses	52	80
Deductions - write-offs	(2,293)	(2,879)	(3,406)
Ending Balance	6,183	7,137	7,931
Inventory - reserve for slow-moving inventory [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	15,944	22,288	22,148
Additions - Charged to expense	3,750	1,646	5,138
Due to acquired businesses	632	129
Deductions - write-offs	(7,317)	(8,119)	(4,998)
Ending Balance	$ 13,009	$ 15,944	$ 22,288