Intangible Assets (Details) (USD $)	3 Months Ended		6 Months Ended			6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	3 Months Ended			6 Months Ended		18 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2012	Jan. 31, 2011	Jul. 31, 2011	Jan. 31, 2012 Technologies [Member] years	Jul. 31, 2011 Technologies [Member] years	Jan. 31, 2012 Customer relationships [Member] years	Jul. 31, 2011 Customer relationships [Member] years	Jan. 31, 2012 Trademarks and other [Member] years	Jul. 31, 2011 Trademarks and other [Member] years	Jan. 31, 2012 Acquisition of Stampede Technologies, Inc. [Member]	Jan. 31, 2011 Acquisition of Stampede Technologies, Inc. [Member]	Oct. 31, 2010 Acquisition of Stampede Technologies, Inc. [Member] years	Jan. 31, 2012 Acquisition of Stampede Technologies, Inc. [Member] years	Jan. 31, 2011 Acquisition of Stampede Technologies, Inc. [Member]	Jan. 31, 2012 Acquisition of Stampede Technologies, Inc. [Member]
Weighted Average Amortization Period						11.7	10.2	10.0	10.0	19.8	18.6
Gross Carrying Amount	$ 83,669,000		$ 83,669,000		$ 83,669,000	$ 47,694,000	$ 47,694,000	$ 29,931,000	$ 29,931,000	$ 6,044,000	$ 6,044,000
Accumulated Amortization	41,610,000		41,610,000		38,199,000	28,724,000	27,000,000	10,757,000	9,281,000	2,129,000	1,918,000
Net Carrying Amount	42,059,000		42,059,000		45,470,000	18,970,000	20,694,000	19,174,000	20,650,000	3,915,000	4,126,000
Effective date of acquisition															October 2010
Name of acquired entity															Stampede Technologies, Inc.
Aggregate purchase price														5,303,000
Fair value of contingent consideration arrangement														3,803,000
Term, in years, of contingent consideration arrangement														3
Business acquisition purchase price paid																	1,680,000
Payment of contingent consideration related to business acquisition																	180,000
Business acquisition, contingent consideration at fair value, noncurrent												3,185,000			3,185,000		3,185,000
Business acquisition, contingent consideration at fair value, current	1,070,000		1,070,000		726,000							1,070,000			1,070,000		1,070,000
Business acquisition, contingent consideration at fair value, accretion expense												119,000	115,000		241,000	153,000	632,000
Useful life of technologies acquired, in years															5
Amortization Expense	1,692,000	2,004,000	3,411,000	3,891,000
Amortization Expense - Current Fiscal Year			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