Segment Information - Additional Information (Detail)	12 Months Ended
	Sep. 30, 2014 Segment	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting Information [Line Items]
Number of reportable segments	3
Concentration of risk, percentage	100.00%	100.00%	100.00%
Credit Concentration Risk
Segment Reporting Information [Line Items]
Concentration of risk, percentage	15.00%	16.00%	18.00%
Sales Revenue, Services, Net
Segment Reporting Information [Line Items]
Concentration risk, number of customers	0	0	0
Number of credit reporting agencies substantial revenues derived from	3
Sales Revenue, Services, Net | Applications
Segment Reporting Information [Line Items]
Concentration of risk, percentage	64.00%	64.00%	63.00%
Sales Revenue, Services, Net | Applications | Fraud Solutions
Segment Reporting Information [Line Items]
Concentration of risk, percentage	23.00%	22.00%	25.00%
Sales Revenue, Services, Net | Applications | Customer Management Solutions
Segment Reporting Information [Line Items]
Concentration of risk, percentage	10.00%	11.00%	13.00%
Sales Revenue, Services, Net | Applications | Collections & Recovery solutions
Segment Reporting Information [Line Items]
Concentration of risk, percentage	9.00%	9.00%	8.00%
Accounts Receivable
Segment Reporting Information [Line Items]
Concentration risk, number of customers	0	0
Property Plant and Equipment
Segment Reporting Information [Line Items]
Concentration risk, number of countries	0	0