Variable Interest Entities (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Mar. 31, 2013
Variable Interest Entity [Line Items]
Securities retained by TMCC	$ 740	$ 466
Variable Interest Entities Securitized Assets [Member]
Variable Interest Entity [Line Items]
Restricted Cash	504	491
Gross Securitized Assets	9,249	8,299
Net Securitized Assets	8,958	7,990
Other assets	9	12
Variable Interest Entities Securitized Assets [Member] | Retail Finance Receivables [Member]
Variable Interest Entity [Line Items]
Restricted Cash	477	458
Gross Securitized Assets	8,725	7,669
Net Securitized Assets	8,605	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	524	630
Net Securitized Assets	353	434
Other assets	6	9
Related Liabilities [Member]
Variable Interest Entity [Line Items]
Debt	7,628	7,009
Other Liabilities	1	1
Related Liabilities [Member] | Retail Finance Receivables [Member]
Variable Interest Entity [Line Items]
Debt	7,437	6,738
Other Liabilities	1	1
Related Liabilities [Member] | Investments In Operating Leases, Net [Member]
Variable Interest Entity [Line Items]
Debt	191	271
Other Liabilities	$ 0	$ 0