Consolidated Balance Sheet (Supplemental) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Statement of Financial Position [Abstract]
Variable Interest Entities Assets Liabilities	The following table presents the assets and liabilities of our consolidated variable interest entities. The assets of the variable interest entities can only be used to settle obligations of the consolidated variable interest entities, and the creditors (or beneficial interest holders) do not have recourse to our general credit. These assets and liabilities are included in the consolidated balance sheet above.
ASSETS
Finance receivables, net	$ 58,042	$ 57,736
Total assets	88,913	91,704
LIABILITIES
Debt	73,234	77,282
Other liabilities	2,605	3,142
Total liabilities	81,251	84,848
Variable Interest Entity, Primary Beneficiary [Member]
ASSETS
Finance receivables, net	10,530	11,317
Total assets	10,530	11,317
LIABILITIES
Debt	9,789	10,626
Other liabilities	2	3
Total liabilities	$ 9,791	$ 10,629