NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - ADDITIONAL INFORMATION (Details)	3 Months Ended	12 Months Ended
	Sep. 30, 2018 USD ($) patent institution $ / shares	Sep. 30, 2018 USD ($) segment patent institution $ / shares	Sep. 30, 2017 USD ($) $ / shares	Sep. 30, 2016 USD ($)	Oct. 01, 2018 USD ($)	Oct. 01, 2017 USD ($)
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Number of financial institutions signed agreements to deploy mobile deposit | institution	6,100	6,100
Number of patents granted | patent	49	49
Number of patent applications pending | patent	21	21
Foreign currency translation adjustment		$ (723,000)	$ 208,000	$ (46,000)
Other-than-temporary impairment charges recognized		0	0	0
Write-offs of allowance for doubtful accounts		0	0	0
Allowance for doubtful accounts receivable	$ 262,000	$ 262,000	31,000
Deferred software maintenance fees amortization period		1 year
Depreciation and other amortization		$ 615,000	322,000	790,000
Total repairs and maintenance expenses		100,000	200,000	200,000
Impairment charges		0	0	0
Software development costs capitalized	0	0	0
Amortization expense from capitalized software costs or purchased technology		0	0	0
Capitalized software development costs for internal use	900,000	900,000	0
Amortization expense for capitalized software development costs for internal use		$ 100,000	$ 0	0
Number of operating segments | segment		1
Number of reporting units | segment		1
Goodwill impairment	$ 0
Common stock, par value (in dollars per share) | $ / shares	$ 0.001	$ 0.001	$ 0.001
Impairment charges related to intangible assets		$ 0	$ 0	0
Advertising costs		500,000	300,000	$ 200,000
Accumulated other comprehensive income (loss)	$ (586,000)	$ (586,000)	147,000
ASU 2016-09
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment of new accounting pronouncement in the period of adoption			8,255,000
ASU 2016-09 | Retained Earnings
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment of new accounting pronouncement in the period of adoption			$ 8,255,000			$ 8,300,000
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	$ 800,000	$ 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	300,000	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	$ 500,000	$ 500,000
Performance Shares
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Trading-day average stock price period		20 days
Minimum
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives		3 years
Minimum | ASC Topic 606 | Scenario, Forecast | Retained Earnings
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment of new accounting pronouncement in the period of adoption					$ 1,200,000
Cumulative-effect adjustment of new accounting pronouncement, net of income tax					800,000
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 | ASC Topic 606 | Scenario, Forecast | Retained Earnings
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment of new accounting pronouncement in the period of adoption					2,000,000.0
Cumulative-effect adjustment of new accounting pronouncement, net of income tax					$ 1,400,000
Maximum | ICAR | Spanish Government Agencies
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Repayment period of loan agreements		12 years