Debt - Outstanding (Details) - USD ($)	3 Months Ended
Debt - Outstanding (Details) - USD ($)	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Debt Instrument [Line Items]
Debt outstanding	$ 5,130,800,000		$ 5,147,200,000
Less short-term debt and current portion of long-term debt	(70,600,000)		(70,600,000)
Total long-term debt	5,060,200,000		5,076,600,000
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax	37,100,000	$ (11,100,000)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax	(27,800,000)	$ 8,300,000
Interest Rate Swap
Debt Instrument [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	64,300,000
2021 Interest Rate Swap
Debt Instrument [Line Items]
Derivative, Notional Amount	$ 1,548,000,000
2021 Interest Rate Swap \| Minimum
Debt Instrument [Line Items]
Derivative, Fixed Interest Rate	1.38%
2021 Interest Rate Swap \| Maximum
Debt Instrument [Line Items]
Derivative, Fixed Interest Rate	1.3915%
Senior Secured Term Loan B-5
Debt Instrument [Line Items]
Debt outstanding	$ 104,300,000		$ 104,300,000
Debt Instrument, Maturity Date	Nov. 15, 2026
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	6.17%		6.21%
Debt Instrument, Unamortized Discount (Premium), Net	$ 100,000		$ 100,000
Debt Issuance Costs, Noncurrent, Net	100,000		200,000
Senior Secured Term Loan B-7
Debt Instrument [Line Items]
Debt outstanding	$ 1,860,800,000		$ 1,864,800,000
Debt Instrument, Maturity Date	Jun. 24, 2031
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	6.07%		6.11%
Debt Instrument, Unamortized Discount (Premium), Net	$ 7,600,000		$ 7,900,000
Debt Issuance Costs, Noncurrent, Net	12,400,000		12,900,000
Senior Secured Revolving Credit Facility
Debt Instrument [Line Items]
Debt outstanding	0		0
Senior Secured Term Loan A-4
Debt Instrument [Line Items]
Debt outstanding	$ 1,264,000,000		$ 1,271,900,000
Debt Instrument, Maturity Date	Jun. 24, 2029
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	5.57%		5.86%
Debt Instrument, Unamortized Discount (Premium), Net	$ 300,000		$ 400,000
Debt Issuance Costs, Noncurrent, Net	3,200,000		3,300,000
Senior Secured Term Loan B-8
Debt Instrument [Line Items]
Debt outstanding	$ 1,901,700,000		$ 1,906,200,000
Debt Instrument, Maturity Date	Jun. 24, 2031
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	6.07%		6.11%
Debt Instrument, Unamortized Discount (Premium), Net	$ 4,000,000.0		$ 4,200,000
Debt Issuance Costs, Noncurrent, Net	$ 5,900,000		$ 6,100,000

TransUnion 10-Q