Segment Information - Additional Information (Details)	12 Months Ended
	Sep. 30, 2019 Segment customer	Sep. 30, 2018 customer	Sep. 30, 2017
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	18.00%	17.00%	19.00%
Revenue Benchmark | Product Concentration Risk | Applications | Customer Cummunication Services
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	9.00%	10.00%	10.00%
Revenue Benchmark | Product Concentration Risk | Applications | Customer Management Solutions
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	6.00%	8.00%	8.00%
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