Finance Receivables, Net (Credit Quality Indicator) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Mar. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Current	$ 65,189	$ 65,180
30-59 Days Past Due	534	469
60-89 Days Past Due	122	92
90 Days or Greater Past Due	38	33
Total Finance Receivables	65,883	65,774
Wholesale [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	9,149	9,436
30-59 Days Past Due	0	0
60-89 Days Past Due	0	0
90 Days or Greater Past Due	0	0
Total Finance Receivables	9,149	9,436
Wholesale [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	8,145	8,129
Wholesale [Member] | Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	972	1,282
Wholesale [Member] | At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	31	24
Wholesale [Member] | Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	1	1
Real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	4,644	4,653
30-59 Days Past Due	4	4
60-89 Days Past Due	0	1
90 Days or Greater Past Due	1	0
Total Finance Receivables	4,649	4,658
Real estate [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	3,977	3,791
Real estate [Member] | Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	644	855
Real estate [Member] | At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	23	12
Real estate [Member] | Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	5	0
Working capital [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	1,872	1,831
30-59 Days Past Due	0	0
60-89 Days Past Due	0	0
90 Days or Greater Past Due	0	0
Total Finance Receivables	1,872	1,831
Working capital [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	1,741	1,642
Working capital [Member] | Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	104	158
Working capital [Member] | At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	25	25
Working capital [Member] | Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	2	6
Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	49,078	48,828
30-59 Days Past Due	522	459
60-89 Days Past Due	121	90
90 Days or Greater Past Due	37	33
Total Finance Receivables	49,758	49,410
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	446	432
30-59 Days Past Due	8	6
60-89 Days Past Due	1	1
90 Days or Greater Past Due	0	0
Total Finance Receivables	$ 455	$ 439