Auto Loans Receivable - Components Of Receivables, Net Of Allowances For Expected Credit Losses (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Receivables [Abstract]
Total auto loans receivable	$ 451.2	$ 377.0
Accrued interest and fees	4.8	4.4
Deferred loan origination costs	1.6	0.5
Less: unearned discounts	(8.9)	(21.3)
Less: allowances for expected credit losses	(46.3)	(57.5)	$ 0.0
Auto loans receivable, net	$ 402.4	$ 303.1