Nature of Operations and Summary of Significant Accounting Policies - Potentially Dilutive Common Shares Excluded from Calculation of Net Loss per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	2,065	4,227	1,873	4,227
Stock options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	207	1,664	270	1,664
RSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	1,718	2,498	1,577	2,498
ESPP common stock equivalents
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	73	65	0	65
Performance RSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	67	0	26	0