Number of dealerships acquired.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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Amount of liabilities incurred for goods and services received that are used in an entity's business and related party payables, assumed at the acquisition date.

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase.

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ACQUISITIONS - Other Acquisitions (Details) $ in Millions	1 Months Ended	12 Months Ended
ACQUISITIONS - Other Acquisitions (Details) $ in Millions	Feb. 14, 2024 USD ($) dealership	Dec. 31, 2023 USD ($) dealership	Dec. 31, 2022 USD ($) dealership	Dec. 31, 2021 USD ($) dealership
Business Acquisition
Additions through acquisitions		$ 49.7	$ 246.3
Cash paid to acquire business		366.1	528.7	$ 1,099.6
Other Acquisitions
Business Acquisition
Aggregate consideration paid for dealerships				166.8
Additions through acquisitions				$ 70.1
U.S.
Business Acquisition
Additions through acquisitions		$ 49.7	$ 236.1
U.S. \| Other Acquisitions
Business Acquisition
Number of dealerships acquired \| dealership		6	6	5
Aggregate consideration paid for dealerships		$ 365.8	$ 507.5
Additions through acquisitions		49.7	236.1
U.S. \| Other Acquisitions \| Subsequent Event
Business Acquisition
Number of dealerships acquired \| dealership	5
Aggregate consideration paid for dealerships	$ 273.3
U.K.
Business Acquisition
Additions through acquisitions		$ 0.0	10.2
U.K. \| Other Acquisitions
Business Acquisition
Number of dealerships acquired \| dealership				7
Aggregate consideration paid for dealerships			34.1
Additions through acquisitions			10.2
Cash paid to acquire business			32.9
Accounts payable			$ 1.2