Consolidated Balance Sheet (Supplemental) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
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 any variable interest entity can only be used to settle obligations of that respective variable interest entity, and the creditors (or beneficial interest holders) do not have recourse to us or to our other assets. These assets and liabilities are included in the consolidated balance sheet above.
ASSETS
Finance receivables, net	$ 62,567	$ 58,042
Investments in operating leases, net	20,384	18,743
Other Assets	1,740	1,727
Total assets	95,302	88,913
LIABILITIES
Debt	78,832	73,234
Other liabilities	2,677	2,605
Total liabilities	87,745	81,251
Variable Interest Entity, Primary Beneficiary [Member]
ASSETS
Finance receivables, net	7,556	10,527	[1]
Investments in operating leases, net	434	0	[1]
Other Assets	12	3	[1]
Total assets	8,002	10,530	[1]
LIABILITIES
Debt	7,009	9,789	[1]
Other liabilities	1	2	[1]
Total liabilities	$ 7,010	$ 9,791	[1]

[1]   Certain prior period amounts have been reclassified to conform to the current presentation.