Revenue Recognition - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Total revenue	$ 23,192	$ 19,983	$ 45,259	$ 37,666
Deposits revenue
Disaggregation of Revenue [Line Items]
Total revenue	14,622	12,908	29,273	24,778
Identity verification revenue
Disaggregation of Revenue [Line Items]
Total revenue	8,570	7,075	15,986	12,888
Transferred at Point in Time | Deposits software and hardware
Disaggregation of Revenue [Line Items]
Total revenue	10,317	9,215	20,600	18,265
Transferred at Point in Time | Identity verification software and hardware
Disaggregation of Revenue [Line Items]
Total revenue	1,136	1,370	2,368	2,315
Transferred over Time | Deposits services and other
Disaggregation of Revenue [Line Items]
Total revenue	4,305	3,693	8,673	6,513
Transferred over Time | Identity verification services and other
Disaggregation of Revenue [Line Items]
Total revenue	$ 7,434	$ 5,705	$ 13,618	$ 10,573