Revenues - Contract Balances (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Contract Balances
Accounts receivable	$ 1,046.2	$ 1,070.3
Unearned revenues	325.1	299.3
Contracts in transit
Contract Balances
Accounts receivable	256.6	272.2
Vehicle receivables
Contract Balances
Accounts receivable	150.7	141.5
Manufacturer receivables
Contract Balances
Accounts receivable	260.7	256.4
Trade receivables
Contract Balances
Accounts receivable	$ 354.6	$ 381.6

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

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-Topic 606
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Balance Type:	credit
Period Type:	instant