Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Sep. 30, 2024
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			$ 4,318.8				$ 4,318.8
Other comprehensive income (loss)	$ (29.0)			$ 5.7			26.7	$ (29.8)
Ending balance	4,578.5						4,578.5
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	71.2			77.6			391.9	201.8
Accumulated Other Comprehensive Loss
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(311.6)	$ (355.7)	(367.2)	(295.8)	$ (262.8)	$ (260.9)	(367.2)	(260.9)
Other comprehensive income (loss)	(28.8)	44.1	11.5	6.3	(33.0)	(1.9)
Ending balance	(340.4)	(311.6)	(355.7)	(289.5)	(295.8)	(262.8)	(340.4)	(289.5)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(16.6)	61.1	28.8	28.9	(10.2)	21.1
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(12.3)	(17.1)	(17.1)	(23.2)	(23.1)	(23.3)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(29.0)	44.0	11.7	5.7	(33.3)	(2.2)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	0.1	0.1	(0.2)	0.6	0.3	0.3
Foreign Currency Translation Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(344.7)	(410.9)	(450.2)	(414.2)	(393.6)	(383.4)	(450.2)	(383.4)
Ending balance	(364.2)	(344.7)	(410.9)	(360.3)	(414.2)	(393.6)	(364.2)	(360.3)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(19.6)	66.1	39.5	53.3	(21.0)	(10.6)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0.0	0.0	0.0	0.0	0.0	0.0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(19.6)	66.1	39.5	53.3	(21.0)	(10.6)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	0.1	0.1	(0.2)	0.6	0.3	0.3
Net Unrealized (Loss)/Gain On Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	32.9	55.0	82.8	118.0	130.3	122.0	82.8	122.0
Ending balance	23.5	32.9	55.0	70.3	118.0	130.3	23.5	70.3
Other Comprehensive Income (Loss), before Reclassifications, before Tax	3.0	(5.0)	(10.7)	(24.5)	10.8	31.6
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(12.3)	(17.1)	(17.1)	(23.2)	(23.1)	(23.3)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(9.4)	(22.1)	(27.8)	(47.7)	(12.3)	8.3
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	0.0	0.0	0.0	0.0	0.0	0.0
Net Unrealized Gain/(Loss) On Available-for-sale Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2
Ending balance	0.1	0.2	0.2	0.3	0.2	0.2	$ 0.1	$ 0.3
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(0.1)	0.0	0.0	0.1	0.0	0.0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0.0	0.0	0.0	0.0	0.0	0.0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(0.1)	0.0	0.0	0.1	0.0	0.0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ 0.0	$ 0.0	$ 0.0	$ 0.0	$ 0.0	$ 0.0

TransUnion 10-Q