Revenue from Contracts with Customers - Disaggregated Revenue (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2022 USD ($) customer	Sep. 30, 2021 USD ($) customer	Sep. 30, 2020 USD ($) customer
Disaggregation of Revenue [Line Items]
Revenue	$ 1,377,270	$ 1,316,536	$ 1,294,562
Revenue from Contract with Customer Benchmark | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	100.00%	100.00%	100.00%
Revenue from Contract with Customer Benchmark | Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration risk, number of customers | customer	2	2	1
Accounts Receivable | Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration risk, number of customers | customer	0	1
Scores
Disaggregation of Revenue [Line Items]
Revenue	$ 706,643	$ 654,147	$ 528,547
Software
Disaggregation of Revenue [Line Items]
Revenue	$ 670,627	$ 662,389	$ 766,015
TransUnion Equifax and Experian customers | Revenue from Contract with Customer Benchmark | Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	39.00%	38.00%	33.00%
On-Premises Software
Disaggregation of Revenue [Line Items]
Revenue	$ 280,649	$ 266,452	$ 347,532
On-Premises Software | Revenue from Contract with Customer Benchmark | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	50.00%	51.00%	59.00%
SaaS Software
Disaggregation of Revenue [Line Items]
Revenue	$ 284,102	$ 251,436	$ 237,044
SaaS Software | Revenue from Contract with Customer Benchmark | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	50.00%	49.00%	41.00%
On-premises and SaaS software
Disaggregation of Revenue [Line Items]
Revenue	$ 564,751	$ 517,888	$ 584,576
On-premises and SaaS software | Revenue from Contract with Customer Benchmark | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	100.00%	100.00%	100.00%
On-premises and SaaS software | Transferred at Point in Time
Disaggregation of Revenue [Line Items]
Revenue	$ 75,647	$ 59,024	$ 127,666
On-premises and SaaS software | Transferred at Point in Time | Revenue from Contract with Customer Benchmark | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	13.00%	11.00%	22.00%
On-premises and SaaS software | Transferred over Time
Disaggregation of Revenue [Line Items]
Revenue	$ 489,104	$ 458,864	$ 456,910
On-premises and SaaS software | Transferred over Time | Revenue from Contract with Customer Benchmark | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	87.00%	89.00%	78.00%
Platform Software
Disaggregation of Revenue [Line Items]
Revenue	$ 116,252	$ 66,884	$ 65,665
Platform Software | Revenue from Contract with Customer Benchmark | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	21.00%	13.00%	11.00%
Non-Platform Software
Disaggregation of Revenue [Line Items]
Revenue	$ 448,499	$ 451,004	$ 518,911
Non-Platform Software | Revenue from Contract with Customer Benchmark | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	79.00%	87.00%	89.00%
Business-to-business Scores
Disaggregation of Revenue [Line Items]
Revenue	$ 475,442	$ 446,538	$ 381,929
Business-to-business Scores | Revenue from Contract with Customer Benchmark | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	67.00%	68.00%	72.00%
Business-to-consumer Scores
Disaggregation of Revenue [Line Items]
Revenue	$ 231,201	$ 207,609	$ 146,618
Business-to-consumer Scores | Revenue from Contract with Customer Benchmark | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	33.00%	32.00%	28.00%
Scores Products
Disaggregation of Revenue [Line Items]
Revenue	$ 706,643	$ 654,147	$ 528,547
Scores Products | Revenue from Contract with Customer Benchmark | Product Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	100.00%	100.00%	100.00%
Americas
Disaggregation of Revenue [Line Items]
Revenue	$ 1,130,711	$ 1,049,933	$ 992,225
Americas | Revenue from Contract with Customer Benchmark | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	82.00%	80.00%	76.00%
Americas | Scores
Disaggregation of Revenue [Line Items]
Revenue	$ 691,006	$ 633,497	$ 514,909
Americas | Software
Disaggregation of Revenue [Line Items]
Revenue	439,705	416,436	477,316
EMEA
Disaggregation of Revenue [Line Items]
Revenue	$ 147,299	$ 190,396	$ 203,584
EMEA | Revenue from Contract with Customer Benchmark | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	11.00%	14.00%	16.00%
EMEA | Scores
Disaggregation of Revenue [Line Items]
Revenue	$ 4,475	$ 11,881	$ 6,385
EMEA | Software
Disaggregation of Revenue [Line Items]
Revenue	142,824	178,515	197,199
Asia Pacific
Disaggregation of Revenue [Line Items]
Revenue	$ 99,260	$ 76,207	$ 98,753
Asia Pacific | Revenue from Contract with Customer Benchmark | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	7.00%	6.00%	8.00%
Asia Pacific | Scores
Disaggregation of Revenue [Line Items]
Revenue	$ 11,162	$ 8,769	$ 7,253
Asia Pacific | Software
Disaggregation of Revenue [Line Items]
Revenue	$ 88,098	$ 67,438	$ 91,500