Contingencies Contingencies - Level 4 Tag - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Loss Contingencies [Line Items]
Loss Contingency, Loss in Period				$ 30,500,000
Provision for income taxes	$ (23,000,000.0)		$ (39,400,000)	(45,200,000)	$ (39,900,000)
Ramirez v. Trans Union LLC [Member] | Judicial Ruling [Member] | Punitive Damages [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Awarded, Value		$ 52,000,000.0		32,000,000.0
Provision for income taxes				7,600,000
Per person [Member] | Ramirez v. Trans Union LLC [Member] | Judicial Ruling [Member] | Punitive Damages [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Awarded, Value		$ 6,353.08		$ 3,936.88