Stockholders' Equity - Summary of Common Stock Reserved for Future Issuance (Details) - shares	Sep. 30, 2021	Oct. 31, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Common stock reserved for future issuance (in shares)	14,887,549
Common stock warrants
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Common stock reserved for future issuance (in shares)	7,679,228
Stock Options and Performance-Based Units Outstanding
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Common stock reserved for future issuance (in shares)	4,434,366
2019 Incentive Award Plan
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Common stock reserved for future issuance (in shares)	1,931,919
ESPP Plan
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Common stock reserved for future issuance (in shares)	842,036	270,000