Stockholder's Equity (Details Textuals 3) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended			12 Months Ended
	Apr. 14, 2009	Oct. 31, 2013	Apr. 30, 2009	Dec. 31, 2007	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013	Oct. 31, 2014
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting term of second group of options	4 years	4 years
Equity Incentive 2007 Plan
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Maximum vesting term for incentive and non-qualified stock options determined by board of directors				10 years
Share-based compensation arrangement by share-based payment award, award requisite service period				5 years
April 2009 Grants
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Nonqualified stock options to purchase shares, exercise price			$ 15.11
Term for not granting cash salary or bonus compensation in excess of $ 1.00 per year			5 years
Deferred compensation arrangement with individual - requisite service period			5 years
Percentage of total aggregate options vested on April 14, 2010			20.00%
Deferred compensation arrangement with individual - maximum contractual term			Each option became fully vested due to continued service on April 14, 2014, the fifth anniversary of the date of grant.
Total compensation expense to be recognized per grant			$ 26.1
Recognized compensation expense					$ 0.0	$ 7.2	$ 10.2
October 2013 Grants
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Nonqualified stock options to purchase shares, exercise price		$ 35.62
Term for not granting cash salary or bonus compensation in excess of $ 1.00 per year		5 years
Deferred compensation arrangement with individual - requisite service period		5 years
Percentage of total aggregate options vested on April 14, 2010		20.00%
Deferred compensation arrangement with individual - maximum contractual term		Each option will become fully vested, assuming continued service, on April 15, 2019 and December 16, 2018, respectively.
Total compensation expense to be recognized per grant								$ 40.0
Recognized compensation expense		$ 7.5				$ 4.7
Percentage of stock options which would get immediately vested on termination of executive		100.00%
Percentage of stock options which would get immediately vested on change of control		100.00%
Fair value of each option of grant		$ 11.43
Willis J. Johnson | April 2009 Grants
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Nonqualified stock options to purchase shares			4,000,000
A. Jayson Adair | April 2009 Grants
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Nonqualified stock options to purchase shares			4,000,000
A. Jayson Adair | October 2013 Grants
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Nonqualified stock options to purchase shares		2,000,000
Vincent W. Mitz | October 2013 Grants
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Nonqualified stock options to purchase shares		1,500,000