For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=121572278&loc=d3e13531-108611

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
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-Section 50
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Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Segment Information - Additional Information (Details)	12 Months Ended
Segment Information - Additional Information (Details)	Sep. 30, 2020 Segment customer	Sep. 30, 2019 customer	Sep. 30, 2018
Segment Reporting Information [Line Items]
Number of reportable segments \| Segment	3
Revenue Benchmark \| Product Concentration Risk \| Applications \| Fraud Solutions
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	15.00%	18.00%	17.00%
Revenue Benchmark \| Product Concentration Risk \| Applications \| Customer Cummunication Services
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	8.00%	9.00%	10.00%
Revenue Benchmark \| Customer Concentration Risk
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	100.00%	100.00%	100.00%
Accounts Receivable \| Customer Concentration Risk
Segment Reporting Information [Line Items]
Concentration risk, number of customers \| customer	0	0