Auto Loans Receivable - Financing Receivable Credit Quality Indicators (Details) $ in Millions	3 Months Ended
	Mar. 31, 2026 USD ($) fICOScore	Mar. 31, 2025 USD ($)	Dec. 31, 2025 USD ($) fICOScore
Auto Loans Receivable
Auto loans receivable, Originated in current year	$ 445.0		$ 1,482.1
Auto loans receivable, Originated in year before current year	1,350.8		628.5
Auto loans receivable, Originated two years before current year	564.4		88.3
Auto loans receivable, Originated three years before current year	76.5		2.2
Auto loans receivable, Originated four years before current year	1.9		7.7
Auto loans receivable, Originated five years or more before current year	6.1		1.1
Total auto loans receivable	2,444.7		2,209.9
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current-period gross write-offs, 2026 origination	0.0
Current-period gross write-offs, 2025 origination	14.7
Current-period gross write-offs, 2024 origination	12.2
Current-period gross write-offs, 2023 origination	4.3
Current-period gross write-offs, 2022 origination	0.1
Current-period gross write-offs, Prior to 2022 origination	0.5
Current-period gross write-offs	31.8	$ 14.7
Palladium
Auto Loans Receivable
Auto loans receivable, Originated in current year	174.7		569.6
Auto loans receivable, Originated in year before current year	513.3		127.0
Auto loans receivable, Originated two years before current year	113.5		0.0
Auto loans receivable, Originated three years before current year	0.0		0.0
Auto loans receivable, Originated four years before current year	0.0		0.0
Auto loans receivable, Originated five years or more before current year	0.0		0.0
Total auto loans receivable	$ 801.5		$ 696.6
Palladium | Weighted Average
Auto Loans Receivable
Auto loans receivable, FICO Score | fICOScore	733		732
Rhodium
Auto Loans Receivable
Auto loans receivable, Originated in current year	$ 177.7		$ 369.6
Auto loans receivable, Originated in year before current year	340.1		98.9
Auto loans receivable, Originated two years before current year	88.9		10.9
Auto loans receivable, Originated three years before current year	9.5		0.0
Auto loans receivable, Originated four years before current year	0.0		0.0
Auto loans receivable, Originated five years or more before current year	0.0		0.0
Total auto loans receivable	$ 616.2		$ 479.4
Rhodium | Weighted Average
Auto Loans Receivable
Auto loans receivable, FICO Score | fICOScore	693		695
Platinum
Auto Loans Receivable
Auto loans receivable, Originated in current year	$ 88.8		$ 513.1
Auto loans receivable, Originated in year before current year	470.4		359.0
Auto loans receivable, Originated two years before current year	323.1		52.5
Auto loans receivable, Originated three years before current year	45.8		1.0
Auto loans receivable, Originated four years before current year	0.8		1.8
Auto loans receivable, Originated five years or more before current year	1.5		0.3
Total auto loans receivable	$ 930.4		$ 927.7
Platinum | Weighted Average
Auto Loans Receivable
Auto loans receivable, FICO Score | fICOScore	651		651
Gold
Auto Loans Receivable
Auto loans receivable, Originated in current year	$ 2.9		$ 25.5
Auto loans receivable, Originated in year before current year	23.1		43.3
Auto loans receivable, Originated two years before current year	38.7		14.7
Auto loans receivable, Originated three years before current year	12.6		0.6
Auto loans receivable, Originated four years before current year	0.5		3.1
Auto loans receivable, Originated five years or more before current year	2.6		0.5
Total auto loans receivable	$ 80.4		$ 87.7
Gold | Weighted Average
Auto Loans Receivable
Auto loans receivable, FICO Score | fICOScore	623		623
Silver
Auto Loans Receivable
Auto loans receivable, Originated in current year	$ 0.5		$ 3.0
Auto loans receivable, Originated in year before current year	2.8		0.2
Auto loans receivable, Originated two years before current year	0.2		7.8
Auto loans receivable, Originated three years before current year	6.5		0.5
Auto loans receivable, Originated four years before current year	0.5		1.7
Auto loans receivable, Originated five years or more before current year	1.3		0.2
Total auto loans receivable	$ 11.8		$ 13.4
Silver | Weighted Average
Auto Loans Receivable
Auto loans receivable, FICO Score | fICOScore	575		575
Bronze
Auto Loans Receivable
Auto loans receivable, Originated in current year	$ 0.4		$ 1.0
Auto loans receivable, Originated in year before current year	0.9		0.1
Auto loans receivable, Originated two years before current year	0.0		2.3
Auto loans receivable, Originated three years before current year	2.0		0.1
Auto loans receivable, Originated four years before current year	0.1		0.9
Auto loans receivable, Originated five years or more before current year	0.6		0.1
Total auto loans receivable	$ 4.0		$ 4.5
Bronze | Weighted Average
Auto Loans Receivable
Auto loans receivable, FICO Score | fICOScore	548		548
Copper
Auto Loans Receivable
Auto loans receivable, Originated in current year	$ 0.0		$ 0.3
Auto loans receivable, Originated in year before current year	0.2		0.0
Auto loans receivable, Originated two years before current year	0.0		0.1
Auto loans receivable, Originated three years before current year	0.1		0.0
Auto loans receivable, Originated four years before current year	0.0		0.2
Auto loans receivable, Originated five years or more before current year	0.1		0.0
Total auto loans receivable	$ 0.4		$ 0.6
Copper | Weighted Average
Auto Loans Receivable
Auto loans receivable, FICO Score | fICOScore	539		549