BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Statement Of Financial Position [Abstract]
Finance and other receivables, allowance for losses	$ 63.7	$ 65.7
Equipment on operating leases, accumulated depreciation	$ 687.4	$ 664.2
Preferred stock, par value	$ 100	$ 100
Preferred stock, noncumulative and nonvoting	6.00%	6.00%
Preferred stock, shares authorized	450,000	450,000
Preferred stock, shares issued	310,000	310,000
Preferred stock, shares outstanding	310,000	310,000
Common stock, par value	$ 100	$ 100
Common stock, shares authorized	200,000	200,000
Common stock, shares issued	145,000	145,000
Common stock, shares outstanding	145,000	145,000