Nature of Operations and Summary of Significant Accounting Policies - Additional Information (Details) $ / shares in Units, deposit in Billions	3 Months Ended	12 Months Ended
	Sep. 30, 2019 USD ($) patent institution deposit $ / shares	Sep. 30, 2019 USD ($) deposit segment institution patent $ / shares	Sep. 30, 2018 USD ($) $ / shares	Sep. 30, 2017 USD ($)	Oct. 01, 2019 USD ($)	Oct. 23, 2018 $ / shares
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of financial services organizations, leading marketplace and financial technology brands (more than) | institution	6,500	6,500
Number of check deposits processed (over) | deposit	3	3
Number of patents granted | patent	57	57
Number of patent applications pending | patent	25	25
Foreign currency translation adjustment		$ (3,504,000)	$ (723,000)	$ 208,000
Other-than-temporary impairment charges recognized in earnings		0	0	0
Write-offs of allowance for doubtful accounts		100,000	0	0
Allowance for doubtful accounts receivable	$ 200,000	200,000	300,000
Depreciation and amortization of property and equipment		1,388,000	615,000	322,000
Repairs and maintenance expenses		100,000	100,000	200,000
Impairment or long-lived assets		0	0	0
Capitalized software development costs	0	0	0
Amortization expense for capitalized software development costs		0	0	0
Capitalized software development costs for internal use	200,000	200,000	900,000
Amortization expense for capitalized software development costs for internal use		$ 300,000	$ 100,000	0
Number of operating segments | segment		1
Number of reporting units | segment		1
Goodwill impairment	$ 0
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.001	$ 0.001	$ 0.001			$ 0.001
Impairment to intangible assets		$ 0	$ 0	0
Trading-day average stock price period		20 days
Advertising costs		$ 800,000	500,000	$ 300,000
Accumulated other comprehensive loss	$ (4,061,000)	$ (4,061,000)	(586,000)
ICAR | Spanish Government Agencies
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Interest rate of loan agreements	0.00%	0.00%
Total amounts outstanding under loan agreements	$ 600,000	$ 600,000	800,000
ICAR | Spanish Government Agencies | Other Current Liabilities
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Current amount outstanding under loan agreements	200,000	200,000	300,000
ICAR | Spanish Government Agencies | Other Noncurrent Liabilities
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Non-current amount outstanding under loan agreements	$ 400,000	$ 400,000	$ 500,000
Minimum
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives		3 years
Minimum | ASU 2016-02 | Scenario, Forecast
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Lease liabilities					$ 7,900,000
Right-of-use assets					6,500,000
Minimum | ICAR | Spanish Government Agencies
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Repayment period of loan agreements		5 years
Maximum
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives		10 years
Maximum | ASU 2016-02 | Scenario, Forecast
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Lease liabilities					8,400,000
Right-of-use assets					$ 7,000,000.0
Maximum | ICAR | Spanish Government Agencies
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Repayment period of loan agreements		12 years