Inventories (Components of Inventories, net) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Inventory [Line Items]
Total inventories	$ 2,012.6	$ 2,492.9
New vehicles
Inventory [Line Items]
Total inventories	696.8	1,556.6
Used vehicles
Inventory [Line Items]
Total inventories	1,172.6	835.9
Parts and accessories
Inventory [Line Items]
Total inventories	$ 143.2	$ 100.4

Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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