Finance Receivables, Net - Finance Receivable Credit Quality Indicators (Details) - USD ($) $ in Millions	Mar. 31, 2019	Mar. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Current	$ 70,738	$ 69,979
Financing receivables, past due	897	836
Total Finance Receivables	71,635	70,815
Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	53,047	52,559
Financing receivables, past due	892	836
Total Finance Receivables	53,939	53,395
Wholesale [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	10,439	10,513
Financing receivables, past due	1
Total Finance Receivables	10,440	10,513
Wholesale [Member] \| Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	9,155	9,451
Wholesale [Member] \| Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	1,127	946
Wholesale [Member] \| At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	152	75
Wholesale [Member] \| Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	6	41
Real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	4,671	4,630
Total Finance Receivables	4,671	4,630
Real estate [Member] \| Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	4,019	4,070
Real estate [Member] \| Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	554	484
Real estate [Member] \| At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	84	29
Real estate [Member] \| Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	14	47
Working capital [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	2,581	2,277
Financing receivables, past due	4
Total Finance Receivables	2,585	2,277
Working capital [Member] \| Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	2,448	2,118
Working capital [Member] \| Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	70	105
Working capital [Member] \| At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	63	33
Working capital [Member] \| Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance Receivables	4	21
30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	657	613
30-59 Days Past Due [Member] \| Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	657	613
60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	162	158
60-89 Days Past Due [Member] \| Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	162	158
90 Days or Greater Past Due [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	78	65
90 Days or Greater Past Due [Member] \| Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	73	$ 65
90 Days or Greater Past Due [Member] \| Wholesale [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	1
90 Days or Greater Past Due [Member] \| Working capital [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	$ 4

Financing receivables that are current.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7A
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953401-111524

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
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