Fair Value Measurements - Financial Assets and Liabilities Not Carried at Fair Value on Recurring Basis in Consolidated Balance Sheet (Details) - USD ($) $ in Millions	Jun. 30, 2015	Mar. 31, 2015
Carrying value [Member]
Financial liabilities
Commercial paper	$ 26,854	$ 27,006
Unsecured notes and loans payable	52,827	52,388
Secured notes and loans payable	11,996	10,837
Fair value [Member]
Financial liabilities
Commercial paper	26,854	27,006
Unsecured notes and loans payable	53,863	53,808
Secured notes and loans payable	11,970	10,832
Fair value [Member] \| Level 1 [Member]
Financial liabilities
Commercial paper	0	0
Unsecured notes and loans payable	0	0
Secured notes and loans payable	0	0
Fair value [Member] \| Level 2 [Member]
Financial liabilities
Commercial paper	26,854	27,006
Unsecured notes and loans payable	53,206	53,174
Secured notes and loans payable	0	0
Fair value [Member] \| Level 3 [Member]
Financial liabilities
Commercial paper	0	0
Unsecured notes and loans payable	657	634
Secured notes and loans payable	11,970	10,832
Retail Loan [Member] \| Carrying value [Member]
Financial assets
Finance receivables, net	50,210	49,734
Retail Loan [Member] \| Fair value [Member]
Financial assets
Finance receivables, net	50,133	49,887
Retail Loan [Member] \| Fair value [Member] \| Level 1 [Member]
Financial assets
Finance receivables, net	0	0
Retail Loan [Member] \| Fair value [Member] \| Level 2 [Member]
Financial assets
Finance receivables, net	0	0
Retail Loan [Member] \| Fair value [Member] \| Level 3 [Member]
Financial assets
Finance receivables, net	50,133	49,887
Commercial Finance [Member] \| Carrying value [Member]
Financial assets
Finance receivables, net	227	217
Commercial Finance [Member] \| Fair value [Member]
Financial assets
Finance receivables, net	234	223
Commercial Finance [Member] \| Fair value [Member] \| Level 1 [Member]
Financial assets
Finance receivables, net	0	0
Commercial Finance [Member] \| Fair value [Member] \| Level 2 [Member]
Financial assets
Finance receivables, net	0	0
Commercial Finance [Member] \| Fair value [Member] \| Level 3 [Member]
Financial assets
Finance receivables, net	234	223
Wholesale [Member] \| Carrying value [Member]
Financial assets
Finance receivables, net	9,175	9,123
Wholesale [Member] \| Fair value [Member]
Financial assets
Finance receivables, net	9,222	9,176
Wholesale [Member] \| Fair value [Member] \| Level 1 [Member]
Financial assets
Finance receivables, net	0	0
Wholesale [Member] \| Fair value [Member] \| Level 2 [Member]
Financial assets
Finance receivables, net	0	0
Wholesale [Member] \| Fair value [Member] \| Level 3 [Member]
Financial assets
Finance receivables, net	9,222	9,176
Real estate [Member] \| Carrying value [Member]
Financial assets
Finance receivables, net	4,541	4,602
Real estate [Member] \| Fair value [Member]
Financial assets
Finance receivables, net	4,417	4,564
Real estate [Member] \| Fair value [Member] \| Level 1 [Member]
Financial assets
Finance receivables, net	0	0
Real estate [Member] \| Fair value [Member] \| Level 2 [Member]
Financial assets
Finance receivables, net	0	0
Real estate [Member] \| Fair value [Member] \| Level 3 [Member]
Financial assets
Finance receivables, net	4,417	4,564
Working capital [Member] \| Carrying value [Member]
Financial assets
Finance receivables, net	1,829	1,815
Working capital [Member] \| Fair value [Member]
Financial assets
Finance receivables, net	1,810	1,804
Working capital [Member] \| Fair value [Member] \| Level 1 [Member]
Financial assets
Finance receivables, net	0	0
Working capital [Member] \| Fair value [Member] \| Level 2 [Member]
Financial assets
Finance receivables, net	0	0
Working capital [Member] \| Fair value [Member] \| Level 3 [Member]
Financial assets
Finance receivables, net	$ 1,810	$ 1,804

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents unsecured promissory note that provides creditworthy institutions with short-term funds as of the balance sheet date.

No definition available.

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents collateralized debt obligation (backed by pledge, mortgage or other lien on the entity's assets) as of the balance sheet date.

+ References

No definition available.

+ Details

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents debt obligation not collateralized by pledge, mortgage or other lien in the entity's assets as of the balance sheet date.

+ References

No definition available.

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- References

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- Definition

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Glossary Loan

-URI http://asc.fasb.org/extlink&oid=6517073

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