Finance Receivables, Net (Credit Quality Indicator) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Mar. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Current	$ 63,876	$ 62,593
30-59 Days Past Due	499	460
60-89 Days Past Due	112	88
90 Days Past Due	32	31
Total Finance Receivables	64,519	63,172
Wholesale [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	9,451	8,689
30-59 Days Past Due	0	0
60-89 Days Past Due	0	0
90 Days Past Due	0	0
Total Finance Receivables	9,451	8,689	[1]
Wholesale [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	8,622	7,740	[1]
Wholesale [Member] | Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	786	915	[1]
Wholesale [Member] | At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	39	33	[1]
Wholesale [Member] | Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	4	1	[1]
Real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	4,583	4,580
30-59 Days Past Due	1	0
60-89 Days Past Due	0	0
90 Days Past Due	0	0
Total Finance Receivables	4,584	4,580
Real estate [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	4,013	3,968
Real estate [Member] | Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	535	583
Real estate [Member] | At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	28	28
Real estate [Member] | Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	8	1
Working capital [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	1,758	1,726
30-59 Days Past Due	0	0
60-89 Days Past Due	0	0
90 Days Past Due	0	0
Total Finance Receivables	1,758	1,726
Working capital [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	1,656	1,616
Working capital [Member] | Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	72	80
Working capital [Member] | At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	27	28
Working capital [Member] | Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	3	2
Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	47,712	47,236
30-59 Days Past Due	492	454
60-89 Days Past Due	111	87
90 Days Past Due	32	31
Total Finance Receivables	48,347	47,808
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	372	362
30-59 Days Past Due	6	6
60-89 Days Past Due	1	1
90 Days Past Due	0	0
Total Finance Receivables	$ 379	$ 369

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