Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Total revenues	$ 398,688	$ 348,966	$ 1,123,824	$ 1,028,522
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	3	3	2
Revenue from Contract with Customer Benchmark [Member] | Customer Concentration Risk | TransUnion, Equifax and Experian customers
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	42.00%	41.00%	40.00%	39.00%
On-premises and SaaS software
Disaggregation of Revenue [Line Items]
Total revenues	$ 172,059	$ 142,537	$ 471,203	$ 417,963
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	15.00%	14.00%	12.00%	13.00%
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	85.00%	86.00%	88.00%	87.00%
On-Premises | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	47.00%	50.00%	47.00%	49.00%
SaaS Products | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	53.00%	50.00%	53.00%	51.00%
Platform software | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	23.00%	20.00%	23.00%	21.00%
Non-platform software | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	77.00%	80.00%	77.00%	79.00%
Operating Segments | On-premises and SaaS software
Disaggregation of Revenue [Line Items]
Total revenues			$ 471,203	$ 417,963
Americas
Disaggregation of Revenue [Line Items]
Total revenues	$ 345,399	$ 293,223	$ 954,829	$ 837,875
Americas | Revenue from Contract with Customer Benchmark [Member] | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	87.00%	84.00%	85.00%	81.00%
EMEA
Disaggregation of Revenue [Line Items]
Total revenues	$ 32,753	$ 37,375	$ 106,446	$ 111,646
EMEA | Revenue from Contract with Customer Benchmark [Member] | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	8.00%	11.00%	9.00%	11.00%
Asia Pacific
Disaggregation of Revenue [Line Items]
Total revenues	$ 20,536	$ 18,368	$ 62,549	$ 79,001
Asia Pacific | Revenue from Contract with Customer Benchmark [Member] | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	5.00%	5.00%	6.00%	8.00%
Scores
Disaggregation of Revenue [Line Items]
Total revenues	$ 201,778	$ 179,355	$ 578,273	$ 532,584
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	$ 148,128	$ 119,010	$ 417,907	$ 357,221
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%	66.00%	72.00%	67.00%
Scores | Business to consumer Scores
Disaggregation of Revenue [Line Items]
Total revenues	$ 53,650	$ 60,345	$ 160,366	$ 175,363
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%	34.00%	28.00%	33.00%
Scores | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	$ 201,778	$ 179,355	$ 578,273	$ 532,584
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	199,948	177,892	570,284	518,695
Scores | EMEA
Disaggregation of Revenue [Line Items]
Total revenues	1,486	1,051	3,988	3,796
Scores | Asia Pacific
Disaggregation of Revenue [Line Items]
Total revenues	344	412	4,001	10,093
Software
Disaggregation of Revenue [Line Items]
Total revenues	196,910	169,611	545,551	495,938
Software | On-premises and SaaS software
Disaggregation of Revenue [Line Items]
Total revenues	172,059	142,537	471,203	417,963
Software | On-premises and SaaS software | Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Total revenues	25,077	19,869	56,073	53,568
Software | On-premises and SaaS software | Transferred over Time
Disaggregation of Revenue [Line Items]
Total revenues	146,982	122,668	415,130	364,395
Software | On-Premises
Disaggregation of Revenue [Line Items]
Total revenues	80,770	70,689	219,165	205,943
Software | SaaS Products
Disaggregation of Revenue [Line Items]
Total revenues	91,289	71,848	252,038	212,020
Software | Platform software
Disaggregation of Revenue [Line Items]
Total revenues	40,317	27,806	109,827	89,680
Software | Non-platform software
Disaggregation of Revenue [Line Items]
Total revenues	131,742	114,731	361,376	328,283
Software | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	196,910	169,611	545,551	495,938
Software | Operating Segments | On-premises and SaaS software
Disaggregation of Revenue [Line Items]
Total revenues	172,059	142,537	471,203	417,963
Software | Americas
Disaggregation of Revenue [Line Items]
Total revenues	145,451	115,331	384,545	319,180
Software | EMEA
Disaggregation of Revenue [Line Items]
Total revenues	31,267	36,324	102,458	107,850
Software | Asia Pacific
Disaggregation of Revenue [Line Items]
Total revenues	$ 20,192	$ 17,956	$ 58,548	$ 68,908