Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2023	Mar. 31, 2023
Statement of Financial Position [Abstract]
Finance receivables, allowance for credit losses	$ 343	$ 253
Common stock, par value (in dollars per share)	$ 100	$ 100
Common stock, shares authorized (in shares)	15,000,000	15,000,000
Common stock, shares issued (in shares)	13,660,000	13,660,000
Common stock, shares outstanding (in shares)	13,660,000	13,660,000