Intangible Assets - Changes in the Carrying Amount of Goodwill by Reportable Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Goodwill
Beginning balance	$ 2,376.3	$ 2,239.9
Additions	11.8	175.8
Disposals	(10.7)	(9.0)
Foreign currency translation	58.3	(30.4)
Ending balance	2,435.7	2,376.3
Retail Automotive
Goodwill
Beginning balance	1,808.8	1,669.0
Additions	11.8	162.5
Disposals	(10.7)	(6.0)
Foreign currency translation	49.2	(16.7)
Ending balance	1,859.1	1,808.8
Retail Commercial Truck
Goodwill
Beginning balance	497.5	494.3
Additions	0.0	13.3
Disposals	0.0	(3.0)
Foreign currency translation	3.9	(7.1)
Ending balance	501.4	497.5
Other
Goodwill
Beginning balance	70.0	76.6
Additions	0.0	0.0
Disposals	0.0	0.0
Foreign currency translation	5.2	(6.6)
Ending balance	$ 75.2	$ 70.0