STATEMENTS OF INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Interest and fee income	$ 477.9	$ 318.5	$ 300.5
Operating lease and rental revenues	235.4	306.1	333.8
Used truck sales and other revenues	20.8	18.3	81.7
TOTAL INTEREST AND OTHER REVENUES	734.1	642.9	716.0
Interest and other borrowing costs	275.7	138.8	124.5
Depreciation and other rental expenses	189.1	179.6	268.7
Cost of used truck sales and other expenses	15.0	8.6	71.4
Selling, general and administrative expenses	64.5	60.7	57.3
Provision for losses on receivables	8.1	(4.7)	(2.2)
TOTAL EXPENSES	552.4	383.0	519.7
INCOME BEFORE INCOME TAXES	181.7	259.9	196.3
Income taxes	42.2	63.1	48.2
NET INCOME	$ 139.5	$ 196.8	$ 148.1