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STOCK-BASED COMPENSATION - Narrative (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2023 USD ($) component tranche $ / shares shares	Sep. 30, 2022 shares	Sep. 30, 2021 shares	Sep. 30, 2020
2016 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	0	0	0
Stock options outstanding (in shares)	2,100,000
Stock options outstanding (in dollars per share) \| $ / shares	$ 65.08
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period over which awards expired	10 years
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years			4 years
Unrecognized compensation cost related to unvested awards \| $	$ 26.5
Weighted-average compensation cost recognition period	1 year 10 months 24 days
Restricted Stock \| 2020 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	591,838
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Unrecognized compensation cost related to unvested awards \| $	$ 9.2
Weighted-average compensation cost recognition period	1 year 9 months 18 days
Number of components included in award units \| component	2
Increase or decrease in award percentage	25.00%
Performance Share Units \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of units vested	0.00%
Performance Share Units \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of units vested	200.00%
Performance Share Units \| 2020 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	144,136
First Component of Performance Share Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance cycle period of each tranche	3 years
Second Component of Performance Share Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period over which awards expired	3 years
Performance cycle period of each tranche	1 year
Number of tranches in component \| tranche	3