Auto Loans Receivable - Financing Receivable, Allowance for Credit Loss (Details) - USD ($) $ in Millions			12 Months Ended
		Oct. 01, 2022	Dec. 31, 2023	Dec. 31, 2022		Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance as of beginning of year			$ 57.5	$ 0.0
Provision for credit losses			45.9	43.8	[1]	$ 0.0
Initial allowance for purchased credit-deteriorated loans			0.0	21.7
Write-offs			(68.3)	(13.9)
Recoveries	[2]		27.3	5.9
Sold loans			(16.1)	0.0
Balance as of end of year			46.3	57.5		0.0
Sold auto loans receivable, aggregate amortized cost			60.6
Proceeds from the sale of auto loans receivable			68.7	0.0		0.0
Gain on sale of auto loans receivable			$ 8.1	$ 0.0		$ 0.0
CIG Financial Acquisition
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision for credit losses		$ 34.2

[1] (1) Reflects activity that occurred after the acquisition of CIG Financial on October 1, 2022. Provision for credit losses includes initial credit loss expense of $34.2 million associated with the auto loan portfolio acquired as part of the acquisition.

[2] (2) Includes proceeds from the recovery of vehicle collateral, net of costs incurred.