Revenues - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Revenues
Total revenues	$ 7,863.6	$ 7,953.8
Unearned revenue recognized as revenue	$ 123.2
Commercial vehicle distribution and other
Revenues
Payment period	45 days
Total revenues	$ 201.9	211.5
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	$ 72.0	$ 62.9
Finance and insurance, net | Retail Automotive and Retail Commercial Truck Dealership
Revenues
Payment period	30 days
Aggregate reserves relating to chargeback activity	$ 56.1		$ 55.3