Intangible Assets - Narrative (Details) - USD ($)	Sep. 30, 2025	Dec. 31, 2024
Goodwill [Line Items]
Goodwill	$ 2,425,500,000	$ 2,371,300,000
Retail automotive dealership
Goodwill [Line Items]
Goodwill	1,850,700,000
Retail commercial truck dealership
Goodwill [Line Items]
Goodwill	500,200,000
Other
Goodwill [Line Items]
Goodwill	74,600,000
Non-Automotive Investments
Goodwill [Line Items]
Goodwill	$ 0