Revenues - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Revenues
Total revenues	$ 7,604.5	$ 7,447.8
Unearned revenue recognized as revenue	$ 121.7
Commercial vehicle distribution and other
Revenues
Payment period	45 days
Total revenues	$ 211.5	178.0
Vehicle Sales | Retail Automotive and Retail Commercial Truck Dealership
Revenues
Payment period	30 days
Service and parts | Retail Automotive and Retail Commercial Truck Dealership
Revenues
Payment period	30 days
Service and parts | Commercial vehicle distribution and other
Revenues
Total revenues	$ 62.9	$ 67.0
Finance and insurance, net | Retail Automotive and Retail Commercial Truck Dealership
Revenues
Payment period	30 days
Aggregate reserves relating to chargeback activity	$ 50.5		$ 48.2