NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Potentially Dilutive Common Shares Excluded from Calculation of Net Income per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	20,135	18,662	19,257	19,034
Stock options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	352	298	361	523
RSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	2,458	1,731	2,077	2,315
ESPP common stock equivalents
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	125	43	40	32
Performance options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	759	645	729	800
Performance RSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potentially dilutive common shares outstanding (in shares)	1,545	1,049	1,154	468
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	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	7,448