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Segment Information (Details) $ in Millions	3 Months Ended		12 Months Ended
Segment Information (Details) $ in Millions	Mar. 31, 2023 USD ($) segment	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)
Segment Reporting Information
Number of reportable segments \| segment	4
Revenues and segment income by reportable segment
Revenues	$ 7,339.0	$ 6,975.4
Segment income	406.9	497.6
Intersegment Elimination
Revenues and segment income by reportable segment
Revenues	0.0	0.0
Segment income	$ 0.0	0.0
Retail automotive dealership
Segment Reporting Information
Number of reportable segments \| segment	1
Number of operating segments \| segment	6
Revenues and segment income by reportable segment
Revenues	$ 6,299.8	6,029.2	$ 23,700.0
Retail automotive dealership \| Operating segments
Revenues and segment income by reportable segment
Revenues	6,299.8	6,029.2
Segment income	256.7	309.9
Retail commercial truck dealership
Revenues and segment income by reportable segment
Revenues	895.6	792.3
Retail commercial truck dealership \| Operating segments
Revenues and segment income by reportable segment
Revenues	895.6	792.3
Segment income	57.1	58.5
Other \| Operating segments
Revenues and segment income by reportable segment
Revenues	143.6	153.9
Segment income	12.1	10.5
Non-Automotive Investments \| Operating segments
Revenues and segment income by reportable segment
Revenues	0.0	0.0
Segment income	$ 81.0	$ 118.7