Intangible Assets (Details) (USD $)	12 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 82,995,000	$ 83,269,000
Accumulated amortization	56,775,000	50,764,000
Net carrying amount	26,220,000	32,505,000
Amortization of intangibles	6,285,000	6,328,000	6,637,000
Estimated Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization Expense - Year One	6,211,000
Amortization Expense - Year Two	4,962,000
Amortization Expense - Year Three	4,782,000
Amortization Expense - Year Four	4,782,000
Amortization Expense - Year Five	862,000
Technologies [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period	11 years 9 months 18 days	11 years 8 months 12 days
Gross carrying amount	47,370,000	47,494,000
Accumulated amortization	36,240,000	33,264,000
Net carrying amount	11,130,000	14,230,000
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period	10 years 0 months 0 days	10 years 0 months 0 days
Gross carrying amount	29,831,000	29,831,000
Accumulated amortization	18,031,000	15,081,000
Net carrying amount	11,800,000	14,750,000
Trademarks and other [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period	20 years 0 months 0 days	20 years 0 months 0 days
Gross carrying amount	5,794,000	5,944,000
Accumulated amortization	2,504,000	2,419,000
Net carrying amount	$ 3,290,000	$ 3,525,000