Unaudited Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
AUTO LOANS RECEIVABLE, allowance for credit losses	$ 48.1	$ 46.3
PROPERTY AND EQUIPMENT, accumulated depreciation	$ 2,100.0	$ 2,100.0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock authorized (in shares)	1,500,000,000	1,500,000,000
Common stock issued (in shares)	63,562,149	63,562,149
Treasury stock (in shares)	21,938,716	21,917,635