SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Operating Expenses or Earnings Per Share (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2025		Sep. 30, 2024		Sep. 30, 2023
Reclassification [Line Items]
Other costs of services		$ 17,698	$ 16,733	$ 16,580	$ 15,576	$ 16,094	$ 15,287	$ 15,194	$ 13,942	$ 66,587	[1]	$ 60,517	[1]	$ 54,811	[1]
Selling, general and administrative	[1]									$ 114,660		100,785		105,982
As Previously Reported
Reclassification [Line Items]
Other costs of services												16,108		13,306
Selling, general and administrative												145,194		147,487
Adjustment
Reclassification [Line Items]
Other costs of services												44,409		41,505
Selling, general and administrative												$ (44,409)		$ (41,505)

[1] Refer to Note 3 for discussion of the change in the current and prior period presentation.