STOCKHOLDERS’ EQUITY - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023	Oct. 02, 2023	Sep. 30, 2023	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 outstanding stock options and RSUs	$ 31,700		$ 31,700
Weighted average period for unrecognized compensation expense expected to be recognized (in years)			2 years 4 months 24 days
Purchase of common stock (in shares)	484,635		484,635			651,269
Recognized compensation expense	$ 3,888	$ 2,704	$ 7,318	$ 5,146
Options granted (in shares)			0	0
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized compensation expense	0	0	$ 0	$ 0
Unrecognized compensation expense related to options outstanding	$ 0		$ 0
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period for unrecognized compensation expense expected to be recognized (in years)			2 years 7 months 6 days
Awards outstanding (in shares)	2,673,936		2,673,936			2,188,296
Recognized compensation expense	$ 2,600	1,900	$ 4,900	3,500
Unrecognized compensation expense related to nonvested awards	$ 23,300		$ 23,300
Performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period for unrecognized compensation expense expected to be recognized (in years)			2 years
Awards outstanding (in shares)	1,256,663		1,256,663			730,393
Recognized compensation expense	$ 1,300	$ 700	$ 2,300	1,400
Unrecognized compensation expense related to nonvested awards	$ 8,300		$ 8,300
2020 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)					5,108,000		4,500,000
Number of common stock reserved for future grants (in shares)	4,345,217		4,345,217
2020 Plan | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (in shares)	2,448,032		2,448,032
2020 Plan | Performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (in shares)	1,256,663		1,256,663
Prior Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)							107,903
Purchase of common stock (in shares)	267,456		267,456
Prior Plans | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (in shares)	8,850		8,850
ESPP common stock equivalents
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)								1,000,000
Number of common stock reserved for future grants (in shares)	270,876		270,876
Issuance of common stock under employee stock purchase plan (in shares)			729,124
Discount rate from market price, offering date			15.00%
Recognized compensation expense			$ 41	$ 100
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		0
Director Plan | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase of common stock (in shares)	177,054		177,054