Allowance for Credit Losses (Past Dues) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Mar. 31, 2014
Past Due Finance Receivables and Investments in Operating Leases
Finance receivables	$ 160	$ 125
Operating leases	45	36
Total	205	161
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	534	469
60-89 Days Past Due	122	92
90 Days or Greater Past Due	38	33
Total Past Due	694	594
Current	65,189	65,180
Total Finance Receivables	65,883	65,774
90 Days or Greater Past Due and Accruing	37	33
Retail Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	522	459
60-89 Days Past Due	121	90
90 Days or Greater Past Due	37	33
Total Past Due	680	582
Current	49,078	48,828
Total Finance Receivables	49,758	49,410
90 Days or Greater Past Due and Accruing	37	33
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	8	6
60-89 Days Past Due	1	1
90 Days or Greater Past Due	0	0
Total Past Due	9	7
Current	446	432
Total Finance Receivables	455	439
90 Days or Greater Past Due and Accruing	0	0
Wholesale [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	0	0
60-89 Days Past Due	0	0
90 Days or Greater Past Due	0	0
Total Past Due	0	0
Current	9,149	9,436
Total Finance Receivables	9,149	9,436
90 Days or Greater Past Due and Accruing	0	0
Real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	4	4
60-89 Days Past Due	0	1
90 Days or Greater Past Due	1	0
Total Past Due	5	5
Current	4,644	4,653
Total Finance Receivables	4,649	4,658
90 Days or Greater Past Due and Accruing	0	0
Working capital [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	0	0
60-89 Days Past Due	0	0
90 Days or Greater Past Due	0	0
Total Past Due	0	0
Current	1,872	1,831
Total Finance Receivables	1,872	1,831
90 Days or Greater Past Due and Accruing	$ 0	$ 0