Non-Controlling Interest - Impact on Equity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Noncontrolling Interest [Abstract]
Net (loss) income attributable to non-controlling interest	$ (493)	$ 1,182	$ (2,042)	$ 3,265
Redemption of common units in i3 Verticals, LLC			(11,714)	(2,597)
Cumulative effect of adoption of new accounting standard			0	640
Allocation of equity to non-controlling interests			10,980	0
Net transfers to (from) non-controlling interests			(734)	(1,960)
Change from net (loss) income attributable to non-controlling interests and transfers to (from) non-controlling interests			$ (2,776)	$ 1,305