STOCKHOLDERS’ EQUITY - Narrative (Details) - USD ($)		12 Months Ended
	Nov. 06, 2018	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	May 13, 2024	Oct. 02, 2023	Sep. 30, 2021	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		$ 21,800,000
Weighted average period for unrecognized compensation expense expected to be recognized		2 years 2 months 12 days
Options to purchase common stock outstanding (in shares)		461,710	651,269	781,092			816,717
Recognized compensation expense		$ 12,624,000	$ 10,463,000	$ 13,346,000
Options granted (in shares)		0	0	0
Amount authorized under share repurchase program					$ 50,000,000
Amount of shares repurchased		$ 24,200,000
Number of shares repurchased (in shares)		2,247,504
Average price of shares repurchased (in dollars per share)		$ 10.78
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 3 months 18 days
Awards outstanding (in shares)		2,453,630	2,188,296	2,441,677			2,411,267
Recognized compensation expense		$ 9,800,000	$ 7,100,000	$ 9,400,000
Unrecognized compensation expense		$ 17,800,000
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 8 months 12 days
Awards outstanding (in shares)		699,458	730,393	919,456			528,724
Recognized compensation expense		$ 1,700,000	$ 2,700,000	$ 3,000,000
Unrecognized compensation expense		3,800,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized compensation expense		0	400,000	500,000
Unrecognized compensation expense related to options outstanding		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		$ 1,000,000	0	100,000
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)		4,671,484
2020 Plan | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (in shares)		2,281,943
2020 Plan | Performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (in shares)		699,458
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)		244,531
Prior Plans | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (in shares)		0
ESPP
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)		182,131
Issuance of common stock under employee stock purchase plan (in shares)		817,869
Discount rate from market price offering date		15.00%
Recognized compensation expense		$ 200,000	$ 300,000	$ 400,000
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)		166,986