Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Supplemental Cash Flow Information [Abstract]
Cash and cash equivalents	$ 60.8	$ 72.6
Restricted cash included in Current Assets	14.3	15.6
Restricted Cash, Noncurrent	1.9	7.2
Total cash, cash equivalents, and restricted cash	77.0	95.4	$ 60.6	$ 569.7
Accrued purchases of property and equipment	38.7	33.0	25.9
Interest payments, net of amounts capitalized and including interest on vehicle inventory financing	310.3	153.7	113.9
Income tax payments, net of income tax refunds	$ 300.8	$ 482.5	$ 458.3