NON-CONTROLLING INTEREST - Ownership Interest (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	[1]	Jun. 30, 2022	Jun. 30, 2021
Noncontrolling Interest [Abstract]
Net loss attributable to non-controlling interest	$ (960)	$ (921)		$ (5,178)	$ (1,918)	[1]
Redemption of common units in i3 Verticals, LLC				(918)	(11,714)
Allocation of equity to non-controlling interests				5,594	12,374
Net transfers to non-controlling interests				4,676	660
Change from net loss attributable to non-controlling interests and transfers from non-controlling interests				$ (502)	$ (1,258)

[1] Effective October 1, 2020, the Company's financial statements are presented in accordance with ASU 2021-08, Accounting Standards Codification Topic 805, Accounting for Contract Assets and Contract Liabilities from Contracts with Customers. See Note 2 to the interim consolidated financial statements for a description of the recently adopted accounting pronouncement and the impacts of adoption on the condensed consolidated statements of operations.