NET LOSS AND UNAUDITED NET LOSS PER SHARE ATTRIBUTABLE TO COMMON STOCKHOLDERS - Antidilutive Securities (Details) - shares	12 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	33,317,966	36,599,202	39,435,334
Outstanding stock options and RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	30,876,381	34,930,053	37,710,621
Employee stock purchase plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	1,659,233	1,310,653	1,447,385
Common stock subject to repurchase
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0	47,691	243,148
Contingently issuable shares pursuant to business combinations
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	748,172	276,625	0
Common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	34,180	34,180	34,180