SEGMENTS - Reportable Segment Performance (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Sep. 30, 2022
Segment Reporting Information [Line Items]
Revenue	$ 86,029	$ 73,939
Other costs of services	(19,069)	(16,510)
Residuals	10,321	8,520
Processing margin	77,281	65,949
Selling, general and administrative	(51,003)	(46,387)
Depreciation and amortization	(8,676)	(6,870)
Change in fair value of contingent consideration	(1,443)	(4,927)
Income (loss) from operations	5,838	(755)
Total assets	869,449	776,436	$ 770,312
Goodwill	398,798	349,597	353,639
Merchant Services
Segment Reporting Information [Line Items]
Revenue	32,834	29,177
Other costs of services	(15,567)	(13,442)
Residuals	9,809	8,181
Processing margin	27,076	23,916
Total assets	206,782	206,780
Goodwill	121,930	119,086	119,086
Software and Services
Segment Reporting Information [Line Items]
Revenue	53,213	44,774
Other costs of services	(3,523)	(3,080)
Residuals	523	343
Processing margin	50,213	42,037
Total assets	607,010	507,399
Goodwill	276,868	230,511
Other
Segment Reporting Information [Line Items]
Revenue	(18)	(12)
Other costs of services	21	12
Residuals	(11)	(4)
Processing margin	(8)	(4)
Total assets	55,657	62,257
Goodwill	$ 0	$ 0	$ 0