Revenues - Retail Commercial Truck Dealership (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Revenues
Total revenues	$ 8,415.6	$ 8,053.0	$ 24,791.9	$ 24,039.3
Retail commercial truck dealership
Revenues
Total revenues	1,123.9	918.6	2,746.3	2,685.9
New truck | Retail commercial truck dealership
Revenues
Total revenues	781.1	620.8	1,776.6	1,803.6
Used truck | Retail commercial truck dealership
Revenues
Total revenues	82.7	60.7	221.5	177.2
Finance and insurance, net | Retail commercial truck dealership
Revenues
Total revenues	5.5	3.7	13.5	12.2
Service and parts | Retail commercial truck dealership
Revenues
Total revenues	250.3	227.0	720.2	675.7
Other | Retail commercial truck dealership
Revenues
Total revenues	$ 4.3	$ 6.4	$ 14.5	$ 17.2