NET LOSS AND UNAUDITED NET LOSS PER SHARE ATTRIBUTABLE TO CLASS A AND CLASS B COMMON STOCKHOLDERS NET LOSS AND UNAUDITED NET LOSS PER SHARE ATTRIBUTABLE TO COMMON STOCKHOLDERS - Pro Forma Antidilutive Securities (Details) (Details) - shares	12 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	39,435,334	116,530,157	112,732,517
Stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	37,710,621	38,432,337	33,039,810
Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0	76,319,511	76,319,511