Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2019
Segment Reporting Information [Line Items]
Revenue	$ 41,111	$ 84,868
Operating expenses
Interchange and network fees	0	55,829
Other costs of services	12,918	9,790
Selling general and administrative	19,287	12,516
Depreciation and amortization	4,655	3,552
Change in fair value of contingent consideration	154	(349)
Income from operations	4,097	3,530
Processing margin	33,497	23,088
Assets	347,186	197,192	$ 349,302
Goodwill	166,413	98,486	168,284
Merchant Services
Segment Reporting Information [Line Items]
Revenue	27,465	77,702
Operating expenses
Interchange and network fees		54,364
Other costs of services	12,113	9,396
Selling general and administrative	6,322	6,091
Depreciation and amortization	2,947	2,782
Change in fair value of contingent consideration	(1,206)	(319)
Income from operations	7,289	5,388
Processing margin	20,896	17,627
Assets	202,580	141,136
Goodwill	106,898	69,666	108,472
Residual expense	5,544	3,685
Proprietary Software and Payments
Segment Reporting Information [Line Items]
Revenue	14,056	7,166
Operating expenses
Interchange and network fees		1,465
Other costs of services	1,215	394
Selling general and administrative	7,936	2,987
Depreciation and amortization	1,539	661
Change in fair value of contingent consideration	1,360	(30)
Income from operations	2,006	1,689
Processing margin	13,009	5,461
Assets	110,570	51,976
Goodwill	59,515	28,820	59,812
Residual expense	168	154
Other
Segment Reporting Information [Line Items]
Revenue	(410)	0
Operating expenses
Interchange and network fees		0
Other costs of services	(410)	0
Selling general and administrative	5,029	3,438
Depreciation and amortization	169	109
Change in fair value of contingent consideration	0	0
Income from operations	(5,198)	(3,547)
Processing margin	(408)	0
Assets	34,036	4,080
Goodwill	0	0	$ 0
Residual expense	$ (408)	$ 0