Inventories (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Inventory [Line Items]
Total inventories	$ 3,630.4	$ 3,509.1
Retail automotive dealership new vehicles
Inventory [Line Items]
Total inventories	1,429.1	1,326.5
Retail automotive dealership used vehicles
Inventory [Line Items]
Total inventories	1,285.5	1,279.6
Retail automotive parts, accessories, and other
Inventory [Line Items]
Total inventories	147.5	145.6
Retail commercial truck dealership vehicles and parts
Inventory [Line Items]
Total inventories	483.3	506.2
Commercial vehicle distribution vehicles, parts, and engines
Inventory [Line Items]
Total inventories	$ 285.0	$ 251.2