Intangible Assets (Details) (USD $)	12 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2009
Gross Carrying Amount	$ 83,669,000	$ 78,199,000
Accumulated Amortization	38,199,000	30,108,000
Net Carrying Amount	45,470,000	48,091,000
Amortization Expense	8,091,000	7,294,000	7,592,000
Amortization Expense - Year One	6,637,000
Amortization Expense - Year Two	6,327,000
Amortization Expense - Year Three	6,285,000
Amortization Expense - Year Four	6,211,000
Amortization Expense - Year Five	4,962,000
Technologies [Member]
Weighted Average Amortization Period	10.2	10.6
Gross Carrying Amount	47,694,000	42,224,000
Accumulated Amortization	27,000,000	22,531,000
Net Carrying Amount	20,694,000	19,693,000
Customer relationships [Member]
Weighted Average Amortization Period	10.0	9.9
Gross Carrying Amount	29,931,000	29,931,000
Accumulated Amortization	9,281,000	6,223,000
Net Carrying Amount	20,650,000	23,708,000
Trademarks and other [Member]
Weighted Average Amortization Period	18.6	17.6
Gross Carrying Amount	6,044,000	6,044,000
Accumulated Amortization	1,918,000	1,354,000
Net Carrying Amount	$ 4,126,000	$ 4,690,000