INTANGIBLE ASSETS - Intangible Assets, net by major class (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Sep. 30, 2023
Finite-Lived intangible assets
Carrying Amount, Gross	$ 378,350	$ 377,994
Accumulated Amortization	(87,019)	(69,566)
Carrying Amount, Net	291,331	308,428
Client relationships
Finite-Lived intangible assets
Carrying Amount, Gross	317,137	316,820
Accumulated Amortization	(68,659)	(54,711)
Carrying Amount, Net	248,478	262,109
Intellectual property
Finite-Lived intangible assets
Carrying Amount, Gross	56,376	56,337
Accumulated Amortization	(15,468)	(12,234)
Carrying Amount, Net	40,908	44,103
Other
Finite-Lived intangible assets
Carrying Amount, Gross	4,837	4,837
Accumulated Amortization	(2,892)	(2,621)
Carrying Amount, Net	$ 1,945	$ 2,216