Revenues - Contract Balances (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Dec. 31, 2021
Contract Balances
Accounts receivable	$ 835.2	$ 734.0
Unearned revenues	296.3	297.0
Unearned revenue recognized as revenue	128.9
Contracts in transit
Contract Balances
Accounts receivable	243.9	198.7
Vehicle receivables
Contract Balances
Accounts receivable	208.2	197.7
Manufacturer receivables
Contract Balances
Accounts receivable	165.0	157.7
Trade receivables
Contract Balances
Accounts receivable	$ 198.9	$ 164.5

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