Earnings (Loss) Per Share Attributable to Common Stockholders - Schedule of Common Stock Equivalents Excluded from Computation of Diluted Earnings (Loss) Per Share (Details) - shares	3 Months Ended
	Oct. 28, 2017	Oct. 29, 2016
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted earnings (loss) per share	60,465,761	61,290,205
Preferred Stock Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted earnings (loss) per share		1,066,225
Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted earnings (loss) per share	954,706	712,925
Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted earnings (loss) per share	59,511,055	59,511,055