Fair Value Measurements - Assets and Liabilities Not Carried at Fair Value on Recurring Basis on Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Mar. 31, 2017	Mar. 31, 2016
Carrying value [Member]
Financial liabilities
Commercial paper	$ 26,632	$ 26,608
Unsecured notes and loans payable	57,282	52,863
Secured notes and loans payable	14,319	14,123
Fair value [Member]
Financial liabilities
Commercial paper	26,632	26,608
Unsecured notes and loans payable	58,223	54,300
Secured notes and loans payable	14,322	14,125
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	26,632	26,608
Unsecured notes and loans payable	55,838	52,913
Secured notes and loans payable	0	0
Fair value [Member] \| Level 3 [Member]
Financial liabilities
Commercial paper	0	0
Unsecured notes and loans payable	2,385	1,387
Secured notes and loans payable	14,322	14,125
Retail Loan [Member] \| Carrying value [Member]
Financial assets
Finance receivables, net	50,682	49,865
Retail Loan [Member] \| Fair value [Member]
Financial assets
Finance receivables, net	50,733	49,551
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	50,733	49,551
Wholesale [Member] \| Carrying value [Member]
Financial assets
Finance receivables, net	10,819	9,160
Wholesale [Member] \| Fair value [Member]
Financial assets
Finance receivables, net	10,881	9,207
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	10,881	9,207
Real estate [Member] \| Carrying value [Member]
Financial assets
Finance receivables, net	4,602	4,590
Real estate [Member] \| Fair value [Member]
Financial assets
Finance receivables, net	4,459	4,277
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	4,459	4,277
Working capital [Member] \| Carrying value [Member]
Financial assets
Finance receivables, net	2,218	1,888
Working capital [Member] \| Fair value [Member]
Financial assets
Finance receivables, net	2,222	1,894
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	$ 2,222	$ 1,894

Fair value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

No definition available.

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- Definition

Fair value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

+ References

No definition available.

+ Details

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- Definition

Including the current and noncurrent portions, fair value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

+ References

No definition available.

+ Details

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- 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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