Investments in Affiliates - Additional information (Detail) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended				6 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2014 @Ventures	Jan. 31, 2013 @Ventures	Jan. 31, 2014 @Ventures	Jan. 31, 2013 @Ventures	Jan. 31, 2014 @Ventures Maximum	Jan. 31, 2014 @Ventures Minimum	Jan. 31, 2014 @Ventures Available For Sale Securities Maximum	Jan. 31, 2014 @Ventures Private Agreements	Jul. 31, 2013 @Ventures Private Agreements
Investment In Unconsolidated Affiliates [Line Items]
Investments in privately held companies					$ 400,000	$ 900,000	$ 400,000	$ 1,500,000
Carrying value of investment												8,100,000	8,000,000
Impairment charges	177,000	1,500,000	177,000	1,500,000	200,000	1,500,000	200,000	1,500,000
Investment distribution income						$ 200,000		$ 200,000
Ownership interest on investment, percent											20.00%
Company's voting interest									50.00%	20.00%