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Stock-Based Compensation (Details Textual) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions			12 Months Ended
	Dec. 14, 2017	Jun. 07, 2016	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Stock-Based Compensation (Textual)
Options exercise price			$ 12.19
Option granted to purchase common stock
Option term, description			Option awards generally vest on a graded basis over three years of service and have ten-year contractual terms.
Fair value of straight line basis, description			Which will be recognized on a straight-line basis over the requisite three-year service period ending in May 2020.
Stock Options [Member]
Stock-Based Compensation (Textual)
Total intrinsic value of options exercised during the period				$ 0.4
Total unrecognized compensation cost			$ 2.0
Non-vested stock options, weighted-average period			1 year
Reduction of exercise price		$ 2.25
Restricted Stock [Member]
Stock-Based Compensation (Textual)
Non-vested stock options, weighted-average period			8 months 12 days
Total unrecognized non-vested stock-based compensation			$ 0.4
Total grant date fair value of shares vested			$ 3.4	$ 4.1	$ 1.3
Class B Common Stock [Member]
Stock-Based Compensation (Textual)
Additional shares available stock option incentive plan for grants	300
Shares of common stock reserved for award under 2015 stock option and incentive plan			1,000
Shares of common stock available for future grants			400
Class B Common Stock [Member] | Stock Options [Member]
Stock-Based Compensation (Textual)
Options expire date	May 01, 2022
Options exercise price	$ 14.93
Option granted to purchase common stock	1,000
Repurchase right number of shares options on May 2, 2019	333,333
Repurchase right number of shares option on May 2, 2020	333,334
Fair value options date of grant	$ 3.3

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The grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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Description of award terms as to how many shares or portion of an award are no longer contingent on satisfaction of either a service condition, market condition or a performance condition, thereby giving the employee the legal right to convert the award to shares, to sell the shares, and be entitled to the cash proceeds of such sale. For example, vesting may be expressed as being 25 percent of the shares under option on each anniversary of the grant date.

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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Number of additional shares authorized for issuance under an established share-based compensation plan.

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