STATEMENTS OF COMPREHENSIVE INCOME AND RETAINED EARNINGS - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022		Jun. 30, 2021
Income Statement [Abstract]
Interest and fee income	$ 74.8	$ 77.4	$ 144.6		$ 154.5
Operating lease and rental revenues	77.0	84.6	156.9		170.4
Used truck sales and other revenues	3.9	44.6	11.4		61.9
TOTAL INTEREST AND OTHER REVENUES	155.7	206.6	312.9		386.8
Interest and other borrowing costs	29.4	32.0	57.3		68.0
Depreciation and other rental expenses	49.3	70.1	86.2		151.3
Cost of used truck sales and other expenses	1.2	42.9	6.0		58.5
Selling, general and administrative expenses	15.2	14.5	30.1		28.1
Provision for losses on receivables	0.1	(0.4)	(2.4)		0.2
TOTAL EXPENSES	95.2	159.1	177.2		306.1
INCOME BEFORE INCOME TAXES	60.5	47.5	135.7		80.7
Income taxes	14.9	11.4	33.3		19.1
NET INCOME	45.6	36.1	102.4		61.6
COMPREHENSIVE INCOME	47.8	35.7	124.1		70.5
RETAINED EARNINGS AT BEGINNING OF PERIOD	1,673.6	1,594.2	1,716.8	[1]	1,668.7
RETAINED EARNINGS AT END OF PERIOD	$ 1,719.2	$ 1,630.3	$ 1,719.2		$ 1,630.3

[1] The December 31, 2021 balance sheet has been derived from audited financial statements.