XML 72 R57.htm IDEA: XBRL DOCUMENT v3.20.2
EQUITY AWARD PLANS - ESPP (Details) - Employee Stock Purchase Plan
3 Months Ended
Oct. 31, 2020
Oct. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term (in years) 11 months 1 day 11 months 1 day
Risk-free interest rate 0.10% 1.90%
Volatility 73.30% 68.70%
Dividend yield 0.00% 0.00%