Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Inventory [Line Items]
Total inventories	$ 4,293.1	$ 3,509.1
Retail automotive dealership new vehicles
Inventory [Line Items]
Total inventories	1,951.3	1,326.5
Retail automotive dealership used vehicles
Inventory [Line Items]
Total inventories	1,186.3	1,279.6
Retail automotive parts, accessories, and other
Inventory [Line Items]
Total inventories	156.2	145.6
Retail commercial truck dealership vehicles and parts
Inventory [Line Items]
Total inventories	543.7	506.2
Commercial vehicle distribution vehicles, parts, and engines
Inventory [Line Items]
Total inventories	$ 455.6	$ 251.2