Allowance for Credit Losses - Allowance for Credit Losses for Finance Receivables and Finance Receivables by Portfolio Segment (Details) - USD ($) $ in Millions	3 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2018
Allowance for Credit Losses for Finance Receivables:
Provision for credit losses	$ 89	$ 85
Finance Receivables:
Total Finance Receivables	71,683		$ 70,815
Retail Loan [Member]
Finance Receivables:
Total Finance Receivables	53,823		53,395
Finance Receivables, Net [Member]
Allowance for Credit Losses for Finance Receivables:
Allowance for credit losses at beginning of period	463	467
Charge-offs	(75)	(79)
Recoveries	14	13
Provision for credit losses	61	52
Allowance for credit losses at end of period	463	453
Ending balance: Individually evaluated for impairment	62	47
Ending balance: Collectively evaluated for impairment	401	406
Finance Receivables:
Total Finance Receivables	71,683	69,650	$ 70,815
Ending balance: Individually evaluated for impairment	482	494
Ending balance: Collectively evaluated for impairment	71,201	69,156
Finance Receivables, Net [Member] \| Retail Loan [Member]
Allowance for Credit Losses for Finance Receivables:
Allowance for credit losses at beginning of period	312	344
Charge-offs	(75)	(79)
Recoveries	14	13
Provision for credit losses	62	44
Allowance for credit losses at end of period	313	322
Ending balance: Individually evaluated for impairment	0	0
Ending balance: Collectively evaluated for impairment	313	322
Finance Receivables:
Total Finance Receivables	53,823	51,375
Ending balance: Individually evaluated for impairment	0	0
Ending balance: Collectively evaluated for impairment	53,823	51,375
Finance Receivables, Net [Member] \| Dealer Products [Member]
Allowance for Credit Losses for Finance Receivables:
Allowance for credit losses at beginning of period	151	123
Charge-offs	0	0
Recoveries	0	0
Provision for credit losses	(1)	8
Allowance for credit losses at end of period	150	131
Ending balance: Individually evaluated for impairment	62	47
Ending balance: Collectively evaluated for impairment	88	84
Finance Receivables:
Total Finance Receivables	17,860	18,275
Ending balance: Individually evaluated for impairment	482	494
Ending balance: Collectively evaluated for impairment	$ 17,378	$ 17,781

Allowance for credit losses for finance receivables.

No definition available.

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- Definition

Notes receivable gross.

+ References

No definition available.

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- Definition

A valuation allowance for financing receivables that are expected to be uncollectible.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
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- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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- Definition

Amount of recovery of financing receivables doubtful of collection that were previously charged off.

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- Definition

Amount of direct write-downs of financing receivables charged against the allowance.

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- Definition

The balance of financing receivables that were collectively evaluated for impairment.

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- Definition

The balance of financing receivables that were individually evaluated for impairment.

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- Definition

Amount representing an agreement for an unconditional promise by the maker to pay the entity (holder) a definite sum of money at a future date. Such amount may include accrued interest receivable in accordance with the terms of the note. The note also may contain provisions and related items including a discount or premium, payable on demand, secured, or unsecured, interest bearing or noninterest bearing, among a myriad of other features and characteristics. Excludes amounts related to receivables held-for-sale.

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Amount of expense related to estimated loss from loan and lease transactions.

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