Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Total revenues	$ 380,266	$ 357,195	$ 725,136	$ 679,556
Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	100.00%	100.00%	100.00%	100.00%
Revenue from Contract with Customer Benchmark [Member] | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	100.00%	100.00%	100.00%	100.00%
Revenue from Contract with Customer Benchmark [Member] | Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Number of Customers	3	2	2	2
Revenue from Contract with Customer Benchmark [Member] | Customer Concentration Risk | TransUnion, Equifax and Experian customers
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	43.00%	39.00%	40.00%	38.00%
On-premises and SaaS software
Disaggregation of Revenue [Line Items]
Total revenues	$ 154,584	$ 149,088	$ 299,144	$ 275,426
On-premises and SaaS software | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	100.00%	100.00%	100.00%	100.00%
On-premises and SaaS software | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk | Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	12.00%	18.00%	10.00%	12.00%
On-premises and SaaS software | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk | Transferred over Time
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	88.00%	82.00%	90.00%	88.00%
On-Premises | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	48.00%	52.00%	46.00%	49.00%
SaaS Products | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	52.00%	48.00%	54.00%	51.00%
Platform software | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	25.00%	27.00%	23.00%	22.00%
Non-platform software | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	75.00%	73.00%	77.00%	78.00%
Operating Segments | On-premises and SaaS software
Disaggregation of Revenue [Line Items]
Total revenues			$ 299,144	$ 275,426
Americas
Disaggregation of Revenue [Line Items]
Total revenues	$ 318,303	$ 279,755	$ 609,430	$ 544,652
Americas | Revenue from Contract with Customer Benchmark [Member] | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	84.00%	78.00%	84.00%	80.00%
EMEA
Disaggregation of Revenue [Line Items]
Total revenues	$ 41,353	$ 35,380	$ 73,693	$ 74,271
EMEA | Revenue from Contract with Customer Benchmark [Member] | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	11.00%	10.00%	10.00%	11.00%
Asia Pacific
Disaggregation of Revenue [Line Items]
Total revenues	$ 20,610	$ 42,060	$ 42,013	$ 60,633
Asia Pacific | Revenue from Contract with Customer Benchmark [Member] | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	5.00%	12.00%	6.00%	9.00%
Scores
Disaggregation of Revenue [Line Items]
Total revenues	$ 198,507	$ 183,742	$ 376,495	$ 353,229
Scores | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	100.00%	100.00%	100.00%	100.00%
Scores | Business to business Scores
Disaggregation of Revenue [Line Items]
Total revenues	$ 144,874	$ 125,243	$ 269,779	$ 238,211
Scores | Business to business Scores | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	73.00%	68.00%	72.00%	67.00%
Scores | Business to consumer Scores
Disaggregation of Revenue [Line Items]
Total revenues	$ 53,633	$ 58,499	$ 106,716	$ 115,018
Scores | Business to consumer Scores | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	27.00%	32.00%	28.00%	33.00%
Scores | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	$ 198,507	$ 183,742	$ 376,495	$ 353,229
Scores | Operating Segments | On-premises and SaaS software
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Scores | Americas
Disaggregation of Revenue [Line Items]
Total revenues	197,039	175,091	370,336	340,803
Scores | EMEA
Disaggregation of Revenue [Line Items]
Total revenues	1,154	1,252	2,502	2,745
Scores | Asia Pacific
Disaggregation of Revenue [Line Items]
Total revenues	314	7,399	3,657	9,681
Software
Disaggregation of Revenue [Line Items]
Total revenues	181,759	173,453	348,641	326,327
Software | On-premises and SaaS software
Disaggregation of Revenue [Line Items]
Total revenues	154,584	149,088	299,144	275,426
Software | On-premises and SaaS software | Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Total revenues	19,193	26,540	30,996	33,699
Software | On-premises and SaaS software | Transferred over Time
Disaggregation of Revenue [Line Items]
Total revenues	135,391	122,548	268,148	241,727
Software | On-Premises
Disaggregation of Revenue [Line Items]
Total revenues	73,473	77,959	138,395	135,254
Software | SaaS Products
Disaggregation of Revenue [Line Items]
Total revenues	81,111	71,129	160,749	140,172
Software | Platform software
Disaggregation of Revenue [Line Items]
Total revenues	38,682	39,802	69,510	61,874
Software | Non-platform software
Disaggregation of Revenue [Line Items]
Total revenues	115,902	109,286	229,634	213,552
Software | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	181,759	173,453	348,641	326,327
Software | Operating Segments | On-premises and SaaS software
Disaggregation of Revenue [Line Items]
Total revenues	154,584	149,088	299,144	275,426
Software | Americas
Disaggregation of Revenue [Line Items]
Total revenues	121,264	104,664	239,094	203,849
Software | EMEA
Disaggregation of Revenue [Line Items]
Total revenues	40,199	34,128	71,191	71,526
Software | Asia Pacific
Disaggregation of Revenue [Line Items]
Total revenues	$ 20,296	$ 34,661	$ 38,356	$ 50,952