Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Numerator
Net income	$ 1,934	$ 2,351
Less: Net income attributable to non-controlling interests	2,083	2,173
Net (loss) income attributable to i3 Verticals, Inc.	$ (149)	$ 178
Denominator
Basic (shares)	14,233,785	8,812,630
Basic (in USD per share)	$ (0.01)	$ 0.02
Dilutive net income per share:
Weighted average shares of Class A coomon stock outstanding (shares)		8,812,630
Weighted average effect of dilutive securities (shares)		1,090,538
Weighted average shares of Class A common stock outstanding - diluted (shares)	14,233,785	9,903,168
Diluted (in USD per share)	$ (0.01)	$ 0.02
Class A Common Stock
Numerator
Net income	$ 1,934	$ 2,351
Less: Net income attributable to non-controlling interests	2,083	2,173
Net (loss) income attributable to i3 Verticals, Inc.	$ (149)	$ 178
Denominator
Basic (shares)	14,233,785	8,812,630
Basic (in USD per share)	$ (0.01)	$ 0.02
Dilutive net income per share:
Net income (loss) attributable to Class A common stockholders - diluted		$ 178