Stockholder's Equity (Details Textuals 1) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			12 Months Ended			82 Months Ended
	Jan. 31, 2018	Oct. 31, 2016	Jul. 31, 2016	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2018	Dec. 30, 2015	Sep. 22, 2011
Stock Repurchase [Abstract]
Additional common stock authorized for repurchase (in shares)									80,000,000
Common stock authorized for repurchase (in shares)									196,000,000
Company repurchased common stock (in shares)				0		5,877,038	106,913,602
Company repurchased common stock						$ 117,900
Shares remaining available for repurchase				89,086,398			89,086,398
Payments Related to Tax Withholding for Share-based Compensation	$ 0	$ 134,615	$ 15,039	$ 1,115	$ 135,433	$ 15,039
Common Stock [Member]
Stock Repurchase [Abstract]
Stock repurchase price per share (in dollars per share)			$ 20.065			$ 20.065
Common Stock [Member] | Dutch Auction [Member]
Stock Repurchase [Abstract]
Common stock authorized for repurchase (in shares)								14,634,146
Company repurchased common stock (in shares)						16,666,666
Stock repurchase price per share (in dollars per share)								$ 19.50
Common Shares Purchased Under Tender Offer, Value						$ 325,000
Common Stock [Member] | Dutch Auction [Member] | Maximum
Stock Repurchase [Abstract]
Stock Repurchase Program, Share Offer Price								20.50
Common Stock [Member] | Dutch Auction [Member] | Minimum
Stock Repurchase [Abstract]
Stock Repurchase Program, Share Offer Price								$ 19.00