Revenue Recognition - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Total revenue	$ 34,714	$ 28,773	$ 67,186	$ 54,748
Deposits revenue
Disaggregation of Revenue [Line Items]
Total revenue	21,305	17,197	40,355	32,812
Identity verification revenue
Disaggregation of Revenue [Line Items]
Total revenue	13,409	11,576	26,831	21,936
Transferred at Point in Time | Deposits software and hardware
Disaggregation of Revenue [Line Items]
Total revenue	16,066	12,134	29,695	22,888
Transferred at Point in Time | Identity verification software and hardware
Disaggregation of Revenue [Line Items]
Total revenue	3,214	879	5,030	2,427
Transferred over Time | Deposits services and other
Disaggregation of Revenue [Line Items]
Total revenue	5,239	5,063	10,660	9,924
Transferred over Time | Identity verification services and other
Disaggregation of Revenue [Line Items]
Total revenue	$ 10,195	$ 10,697	$ 21,801	$ 19,509