Intangible Assets - Changes in Goodwill by Reportable Segment (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Goodwill [Roll Forward]
Goodwill, Beginning balance	$ 1,928,400,000	$ 1,911,000,000
Additions	209,600,000	0
Disposals	(600,000)	(8,800,000)
Foreign currency translation	(13,300,000)	26,200,000
Goodwill, Ending balance	2,124,100,000	1,928,400,000
Retail automotive dealership
Goodwill [Roll Forward]
Goodwill, Beginning balance	1,534,800,000	1,524,800,000
Additions	96,800,000	0
Disposals	(600,000)	(8,800,000)
Foreign currency translation	(8,800,000)	18,800,000
Goodwill, Ending balance	1,622,200,000	1,534,800,000
Retail commercial truck dealership
Goodwill [Roll Forward]
Goodwill, Beginning balance	309,400,000	309,000,000.0
Additions	112,800,000	0
Disposals	0	0
Foreign currency translation	100,000	400,000
Goodwill, Ending balance	422,300,000	309,400,000
Other
Goodwill [Roll Forward]
Goodwill, Beginning balance	84,200,000	77,200,000
Additions	0	0
Disposals	0	0
Foreign currency translation	(4,600,000)	7,000,000.0
Goodwill, Ending balance	79,600,000	84,200,000
Non-Automotive Investments
Goodwill [Roll Forward]
Goodwill, Beginning balance	0
Goodwill, Ending balance	$ 0	$ 0