Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Total revenues	$ 348,966	$ 338,184	$ 1,028,522	$ 981,959
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	2	3
Revenue from Contract with Customer Benchmark [Member] | Customer Concentration Risk | TransUnion, Equifax and Experian customers
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	41.00%	38.00%	39.00%	37.00%
On-premises and SaaS software
Disaggregation of Revenue [Line Items]
Total revenues	$ 142,537	$ 130,230	$ 417,963	$ 382,236
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	14.00%	10.00%	13.00%	10.00%
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	86.00%	90.00%	87.00%	90.00%
On-Premises | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	50.00%	49.00%	49.00%	51.00%
SaaS Products | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	50.00%	51.00%	51.00%	49.00%
Platform software | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	20.00%	11.00%	21.00%	11.00%
Non-platform software | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	80.00%	89.00%	79.00%	89.00%
Operating Segments | On-premises and SaaS software
Disaggregation of Revenue [Line Items]
Total revenues			$ 417,963	$ 382,236
Americas
Disaggregation of Revenue [Line Items]
Total revenues	$ 293,223	$ 269,166	$ 837,875	$ 779,362
Americas | Revenue from Contract with Customer Benchmark [Member] | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	84.00%	80.00%	81.00%	79.00%
EMEA
Disaggregation of Revenue [Line Items]
Total revenues	$ 37,375	$ 47,869	$ 111,646	$ 143,092
EMEA | Revenue from Contract with Customer Benchmark [Member] | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	11.00%	14.00%	11.00%	15.00%
Asia Pacific
Disaggregation of Revenue [Line Items]
Total revenues	$ 18,368	$ 21,149	$ 79,001	$ 59,505
Asia Pacific | Revenue from Contract with Customer Benchmark [Member] | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	5.00%	6.00%	8.00%	6.00%
Scores
Disaggregation of Revenue [Line Items]
Total revenues	$ 179,355	$ 172,202	$ 532,584	$ 485,572
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	$ 119,010	$ 115,862	$ 357,221	$ 335,325
Scores | Business to business Scores | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	66.00%	67.00%	67.00%	69.00%
Scores | Business to consumer Scores
Disaggregation of Revenue [Line Items]
Total revenues	$ 60,345	$ 56,340	$ 175,363	$ 150,247
Scores | Business to consumer Scores | Revenue from Contract with Customer Benchmark [Member] | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	34.00%	33.00%	33.00%	31.00%
Scores | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	$ 179,355	$ 172,202	$ 532,584	$ 485,572
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	177,892	165,539	518,695	468,039
Scores | EMEA
Disaggregation of Revenue [Line Items]
Total revenues	1,051	2,988	3,796	10,343
Scores | Asia Pacific
Disaggregation of Revenue [Line Items]
Total revenues	412	3,675	10,093	7,190
Software
Disaggregation of Revenue [Line Items]
Total revenues	169,611	165,982	495,938	496,387
Software | On-premises and SaaS software
Disaggregation of Revenue [Line Items]
Total revenues	142,537	130,230	417,963	382,236
Software | On-premises and SaaS software | Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Total revenues	19,869	12,566	53,568	37,304
Software | On-premises and SaaS software | Transferred over Time
Disaggregation of Revenue [Line Items]
Total revenues	122,668	117,664	364,395	344,932
Software | On-Premises
Disaggregation of Revenue [Line Items]
Total revenues	70,689	63,536	205,943	193,449
Software | SaaS Products
Disaggregation of Revenue [Line Items]
Total revenues	71,848	66,694	212,020	188,787
Software | Platform software
Disaggregation of Revenue [Line Items]
Total revenues	27,806	14,178	89,680	43,615
Software | Non-platform software
Disaggregation of Revenue [Line Items]
Total revenues	114,731	116,052	328,283	338,621
Software | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	169,611	165,982	495,938	496,387
Software | Operating Segments | On-premises and SaaS software
Disaggregation of Revenue [Line Items]
Total revenues	142,537	130,230	417,963	382,236
Software | Americas
Disaggregation of Revenue [Line Items]
Total revenues	115,331	103,627	319,180	311,323
Software | EMEA
Disaggregation of Revenue [Line Items]
Total revenues	36,324	44,881	107,850	132,749
Software | Asia Pacific
Disaggregation of Revenue [Line Items]
Total revenues	$ 17,956	$ 17,474	$ 68,908	$ 52,315