Variable Interest Entities (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Mar. 31, 2013
Variable Interest Entity [Line Items]
Securities retained by TMCC	$ 929	$ 466
Variable Interest Entities Securitized Assets [Member]
Variable Interest Entity [Line Items]
Restricted Cash	501	491
Gross Securitized Assets	8,732	8,299
Net Securitized Assets	8,481	7,990
Other assets	11	12
Variable Interest Entities Securitized Assets [Member] | Retail Finance Receivables [Member]
Variable Interest Entity [Line Items]
Restricted Cash	474	458
Gross Securitized Assets	8,321	7,669
Net Securitized Assets	8,209	7,556
Other assets	3	3
Variable Interest Entities Securitized Assets [Member] | Investments In Operating Leases, Net [Member]
Variable Interest Entity [Line Items]
Restricted Cash	27	33
Gross Securitized Assets	411	630
Net Securitized Assets	272	434
Other assets	8	9
Related Liabilities [Member]
Variable Interest Entity [Line Items]
Debt	7,118	7,009
Other Liabilities	2	1
Related Liabilities [Member] | Retail Finance Receivables [Member]
Variable Interest Entity [Line Items]
Debt	6,996	6,738
Other Liabilities	2	1
Related Liabilities [Member] | Investments In Operating Leases, Net [Member]
Variable Interest Entity [Line Items]
Debt	122	271
Other Liabilities	$ 0	$ 0