SUPPLEMENTAL BALANCE SHEET INFORMATION - Other Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2025	Sep. 30, 2024
Loss Contingencies [Line Items]
Long-term client deposits	$ 12,127	$ 16,966
Long-term finance leases	2,316	433
Other	510	564
Resolution and Plea Agreements	12,613	17,000
Other long-term liabilities	27,566	34,963
Accrued amount - non-current portion	12,613	17,000
US DOJ Resolution and Plea Agreements
Loss Contingencies [Line Items]
Resolution and Plea Agreements	17,000
Amount paid	5,000	$ 6,500
Loss contingency, estimate of possible loss	$ 17,000
Accrual interest rate (percent)	4.18%
Accrued amount - non-current portion	$ 17,000