Auto Loans Receivable - Financing Receivable, Past Due (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Financing Receivable, Past Due [Line Items]
Total auto loans receivable	$ 2,020.0	$ 1,103.8
Total Past Due
Financing Receivable, Past Due [Line Items]
Total auto loans receivable	48.5	28.8
31-60 Days
Financing Receivable, Past Due [Line Items]
Total auto loans receivable	35.1	20.6
61-90 Days
Financing Receivable, Past Due [Line Items]
Total auto loans receivable	9.8	5.5
Greater than 90 Days
Financing Receivable, Past Due [Line Items]
Total auto loans receivable	3.6	2.7
Current
Financing Receivable, Past Due [Line Items]
Total auto loans receivable	$ 1,971.5	$ 1,075.0