STOCK INCENTIVE PLAN - Stock Options Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Shares
Outstanding, beginning balance (in shares)	425	690	713
Granted (in shares)	0	0	51
Exercised (in shares)	(13)	(253)	(74)
Forfeited (in shares)	0	(12)	0
Outstanding, ending balance (in shares)	412	425	690	713
Exercisable (in shares)	397
Weighted-Average Exercise Price
Outstanding, beginning balance (in dollars per share)	$ 39.59	$ 32.93	$ 26.00
Granted (in dollars per share)	0	0	101.66
Exercised (in dollars per share)	11.18	18.46	13.26
Forfeited (in dollars per share)	0	103.67	0
Outstanding, ending balance (in dollars per share)	40.46	39.59	32.93	$ 26.00
Exercisable (in dollars per share)	38.17
Weighted-Average Grant Date Fair Value
Options outstanding (in dollars per share)	19.56	19.23	16.69	$ 13.29
Granted (in dollars per share)	0	0	54.06
Exercised (in dollars per share)	$ 8.44	$ 10.78	$ 9.56
Stock Options, Additional Disclosures
Outstanding, aggregate intrinsic value	$ 12,238	$ 20,584	$ 80,152	$ 38,062
Exercised, aggregate intrinsic value	888	$ 33,270	$ 9,201
Exercisable, aggregate intrinsic value	$ 12,238
Outstanding, weighted average remaining contractual term (in years)	10 years 10 months 2 days	11 years 6 months 7 days	9 years 9 months	5 years 2 months 19 days
Exercisable, weighted average remaining contractual term (in years)	8 years 5 months 19 days