Fair Value Measurements - Assets and Liabilities Not Carried at Fair Value on Recurring Basis on Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Jun. 30, 2017	Mar. 31, 2017
Carrying value [Member]
Financial liabilities
Commercial paper	$ 26,498	$ 26,632
Unsecured notes and loans payable	58,465	57,282
Secured notes and loans payable	13,813	14,319
Fair value [Member]
Financial liabilities
Commercial paper	26,498	26,632
Unsecured notes and loans payable	59,465	58,223
Secured notes and loans payable	13,832	14,322
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	26,498	26,632
Unsecured notes and loans payable	57,402	55,838
Secured notes and loans payable	0	0
Fair value [Member] \| Level 3 [Member]
Financial liabilities
Commercial paper	0	0
Unsecured notes and loans payable	2,063	2,385
Secured notes and loans payable	13,832	14,322
Retail Loan [Member] \| Carrying value [Member]
Financial assets
Finance receivables, net	50,623	50,682
Retail Loan [Member] \| Fair value [Member]
Financial assets
Finance receivables, net	50,644	50,733
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	50,644	50,733
Wholesale [Member] \| Carrying value [Member]
Financial assets
Finance receivables, net	11,082	10,819
Wholesale [Member] \| Fair value [Member]
Financial assets
Finance receivables, net	11,139	10,881
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	11,139	10,881
Real estate [Member] \| Carrying value [Member]
Financial assets
Finance receivables, net	4,653	4,602
Real estate [Member] \| Fair value [Member]
Financial assets
Finance receivables, net	4,599	4,459
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	4,599	4,459
Working capital [Member] \| Carrying value [Member]
Financial assets
Finance receivables, net	2,260	2,218
Working capital [Member] \| Fair value [Member]
Financial assets
Finance receivables, net	2,280	2,222
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	$ 2,280	$ 2,222

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

No definition available.

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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
-URI http://asc.fasb.org/subtopic&trid=2196772

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