Intangible Assets - Changes in the Carrying Amount of Goodwill by Reportable Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Goodwill
Beginning balance	$ 2,154.7	$ 2,124.1
Additions	95.9	93.8
Disposals	0.0	(1.9)
Impairment	(40.7)	0.0	$ 0.0
Foreign currency translation	25.0	(61.3)
Ending balance	2,234.9	2,154.7	2,124.1
Retail automotive dealership
Goodwill
Beginning balance	1,617.6	1,622.2
Additions	64.3	49.9
Disposals	0.0	(1.9)
Impairment	(40.7)
Foreign currency translation	22.8	(52.6)
Ending balance	1,664.0	1,617.6	1,622.2
Retail commercial truck dealership
Goodwill
Beginning balance	462.3	422.3
Additions	29.9	43.9
Disposals	0.0	0.0
Impairment	0.0
Foreign currency translation	2.1	(3.9)
Ending balance	494.3	462.3	422.3
Other
Goodwill
Beginning balance	74.8	79.6
Additions	1.7	0.0
Disposals	0.0	0.0
Impairment	0.0
Foreign currency translation	0.1	(4.8)
Ending balance	$ 76.6	$ 74.8	$ 79.6