Stockholders' Equity - Summary of Common Stock Reserved for Future Issuance (Details) - shares	Sep. 30, 2020	Oct. 31, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Common stock reserved for future issuance (in shares)	13,423,199
Common stock warrants
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Common stock reserved for future issuance (in shares)	7,604,446
Stock Options and Performance-Based Awards Outstanding
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Common stock reserved for future issuance (in shares)	2,740,255
2019 Incentive Award Plan
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Common stock reserved for future issuance (in shares)	2,518,853
ESPP Plan
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Common stock reserved for future issuance (in shares)	559,645	270,000