Revenues - Contract Balances (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2019	Dec. 31, 2018
Contract Balances
Accounts receivable, net	$ 967.3	$ 929.1
Unearned revenues	279.7	269.8
Revenue recognized from unearned revenue	220.3
Contracts in transit
Contract Balances
Accounts receivable, net	312.2	314.2
Vehicle receivables
Contract Balances
Accounts receivable, net	271.2	266.9
Manufacturer receivables
Contract Balances
Accounts receivable, net	213.8	211.3
Trade receivables
Contract Balances
Accounts receivable, net	$ 158.8	$ 129.1

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Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

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