STOCKHOLDERS’ EQUITY - Narrative (Details) - USD ($)		12 Months Ended
	Nov. 06, 2018	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023	May 13, 2024	Oct. 02, 2023	Sep. 30, 2022	Jan. 31, 2020	Mar. 07, 2018	Mar. 10, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to options outstanding		$ 31,700,000
Weighted average period for unrecognized compensation expense expected to be recognized		2 years 2 months 12 days
Tax benefits related to stock-based compensation expense		$ 1,800,000	$ 2,000,000	$ 1,400,000
Options to purchase common stock outstanding (in shares)		158,589	461,710	651,269			781,092
Recognized compensation expense		$ 16,810,000	$ 12,624,000	$ 10,463,000
Options granted (in shares)		0	0	0
Amount authorized under share repurchase program					$ 50,000,000
Amount of shares repurchased		$ 4,700,000	$ 24,200,000
Number of shares repurchased (in shares)		527,172	2,247,504
Average price of shares repurchased (in dollars per share)		$ 8.98	$ 10.78
Total purchases		$ 29,000,000.0
Inducement Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase common stock outstanding (in shares)		45,000
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period for unrecognized compensation expense expected to be recognized		2 years 6 months
Awards outstanding (in shares)		2,926,842	2,453,630	2,188,296			2,441,677
Recognized compensation expense		$ 10,300,000	$ 9,800,000	$ 7,100,000
Unrecognized compensation expense		$ 18,700,000
RSUs | Inducement Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (in shares)		307,619
Performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period for unrecognized compensation expense expected to be recognized		1 year 9 months 18 days
Awards outstanding (in shares)		2,022,284	699,458	730,393			919,456
Recognized compensation expense		$ 6,000,000	$ 1,700,000	$ 2,700,000
Unrecognized compensation expense		$ 12,800,000
Performance RSUs | Inducement Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (in shares)		1,095,869
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized compensation expense		$ 0	0	400,000
Unrecognized compensation expense related to options outstanding		$ 0
Performance Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase common stock outstanding (in shares)		0
Performance Options | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock reserved for future grants (in shares)	800,000
Recognized compensation expense		$ 0	1,000,000.0	0
Exercise price per share (in dollars per share)	$ 9.50
2020 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)						5,108,000		9,608,000
Number of common stock reserved for future grants (in shares)		2,804,358
2020 Plan | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (in shares)		2,545,394
2020 Plan | Performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (in shares)		926,415
Prior Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)								107,903
Options to purchase common stock outstanding (in shares)		113,589
Prior Plans | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (in shares)		0
ESPP common stock equivalents
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to options outstanding		$ 200,000
Weighted average period for unrecognized compensation expense expected to be recognized		4 months 24 days
Common stock reserved for issuance (in shares)									1,000,000
Number of common stock reserved for future grants (in shares)		6,020
Issuance of common stock under employee stock purchase plan (in shares)		993,980
Discount rate from market price offering date		15.00%
Recognized compensation expense		$ 500,000	$ 200,000	$ 300,000
Director Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)										1,500,000
Number of common stock reserved for future grants (in shares)		0
Director Plan | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase common stock outstanding (in shares)		73,829