Debt - Additional Information (Details) - USD ($) $ in Millions	6 Months Ended
Sep. 30, 2018	Mar. 31, 2018
Debt Instrument [Line Items]
Debt instrument, unamortized premiums, discounts and debt issuance costs	$ 343	$ 353
Commercial paper [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 25,400	27,400
Commercial paper average remaining maturity period	83 days
Unsecured notes and loans payable [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 58,700	57,600
Debt maturity year	2049
Debt denominated in foreign currency	$ 11,700	$ 13,300
Unsecured notes and loans payable [Member] \| Floating and Fixed Rate [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Contractual interest rate	0.00%	0.00%
Unsecured notes and loans payable [Member] \| Floating and Fixed Rate [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Contractual interest rate	5.00%	5.00%
Secured notes and loans payable [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 14,600	$ 13,700
Debt maturity year	2049
Secured notes and loans payable [Member] \| Floating and Fixed Rate [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Contractual interest rate	1.10%	1.10%
Secured notes and loans payable [Member] \| Floating and Fixed Rate [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Contractual interest rate	3.10%	2.50%

Portion of a debt instrument that is denominated in foreign currency.

No definition available.

Name:	tmcc_DebtInstrumentDenominatedInForeignCurrency
Namespace Prefix:	tmcc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The end year for the range of maturity dates on long term debt.

+ References

No definition available.

+ Details

Name:	tmcc_LongTermDebtMaturityDateRangeEndYear
Namespace Prefix:	tmcc_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average remaining maturity period on short term debt.

+ References

No definition available.

+ Details

Name:	tmcc_ShortTermDebtWeightedAverageRemainingMaturityPeriod
Namespace Prefix:	tmcc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of unamortized debt discount (premium) and debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

+ Details

Name:	us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_DebtInstrumentAxis=us-gaap_CommercialPaperMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=us-gaap_UnsecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	tmcc_DebtInterestRateTypeAxis=tmcc_FloatingAndFixedRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=us-gaap_SecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: