Intrinsic value of stock options - Stock-Based Compensation (Details 4) - USD ($)	12 Months Ended
Jul. 31, 2016	Jul. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Aggregate Intrinsic Value of Options Exercised	$ 363,151	$ 129,908
Cash Received for Exercise of Stock Options		$ 6,416

Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration