Intangible Assets (Details) - USD ($)	12 Months Ended
	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 82,995,000	$ 82,995,000
Accumulated amortization	62,986,000	56,775,000
Net carrying amount	20,009,000	26,220,000
Amortization of intangibles	6,211,000	$ 6,285,000	$ 6,328,000
Estimated Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization Expense - Year One	4,962,000
Amortization Expense - Year Two	4,782,000
Amortization Expense - Year Three	4,782,000
Amortization Expense - Year Four	862,000
Amortization Expense - Year Five	$ 862,000
Technologies [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period	12 years 1 month 6 days	11 years 9 months 18 days
Gross carrying amount	$ 47,370,000	$ 47,370,000
Accumulated amortization	39,266,000	36,240,000
Net carrying amount	$ 8,104,000	$ 11,130,000
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period	10 years	10 years
Gross carrying amount	$ 29,831,000	$ 29,831,000
Accumulated amortization	20,981,000	18,031,000
Net carrying amount	$ 8,850,000	$ 11,800,000
Trademarks and other [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period	20 years	20 years
Gross carrying amount	$ 5,794,000	$ 5,794,000
Accumulated amortization	2,739,000	2,504,000
Net carrying amount	$ 3,055,000	$ 3,290,000