Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2025	Mar. 31, 2024
Statement of Financial Position [Abstract]
Finance receivables, allowance for credit losses	$ 1,644	$ 1,637
Common Stock, Par or Stated Value Per Share	$ 0	$ 0
Common Stock, Shares Authorized	100,000	100,000
Common Stock, Shares, Issued	91,500	91,500
Common Stock, Shares, Outstanding	91,500	91,500