Revenues - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Revenues
Total revenues	$ 7,447.8	$ 7,339.0
Unearned revenue recognized as revenue	$ 112.5
Commercial vehicle distribution and other
Revenues
Payment period	45 days
Total revenues	$ 178.0	143.6
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	$ 67.0	$ 61.3
Finance and insurance, net | Retail Automotive and Retail Commercial Truck Dealership
Revenues
Payment period	30 days
Aggregate reserves relating to chargeback activity	$ 48.4		$ 42.7