Commitments and Contingencies - Additional Information (Details) $ in Millions	12 Months Ended
	Sep. 30, 2020 USD ($)
Loss Contingencies [Line Items]
Indemnification period for former officers and members of the boards of directors	6 years
Bellevue, Washington Office Space
Loss Contingencies [Line Items]
Letter of credit as security deposit	$ 1.8
Other Facility
Loss Contingencies [Line Items]
Letter of credit as security deposit	$ 0.3