NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Potentially Dilutive Common Shares Excluded from Calculation of Net Income (Loss) per Share (Details) - shares shares in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	19,085	17,868	17,817
Stock options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	330	335	437
RSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	2,004	1,646	1,455
ESPP common stock equivalents
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	11	8	6
Performance options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	687	680	755
Performance RSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	1,157	303	268
Convertible senior notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	7,448	7,448	7,448
Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	7,448	7,448	7,448