Related Party Transactions - Related Party Transactions Included in Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Sep. 30, 2021	Mar. 31, 2021
Cash and cash equivalents
Cash and cash equivalents	$ 9,490	$ 8,195
TMCC-affiliated companies [Member]
Investments in marketable securities
Commercial paper	8	196
Finance receivables, net
Accounts receivable	81	140
Deferred retail subvention income	(1,018)	(1,156)
Investments in operating leases, net
Investments in operating leases, net	(241)	(236)
Deferred lease subvention income	(1,354)	(1,528)
Other assets
Notes receivable	869	869
Other receivables, net	81	83
Other liabilities
Unearned voluntary protection contract revenues and insurance earned premiums	368	352
Other payables, net	319	306
Notes payable	25	19
Commercial paper [Member] \| TMCC-affiliated companies [Member]
Cash and cash equivalents
Cash and cash equivalents	$ 8	$ 6

Amount of deferred operating lease subvention revenue from related parties.

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Amount of deferred retail subvention revenue from related parties.

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The amount of property, by major property class, net of accumulated depreciation, subject to or available for lease as of the balance sheet date.

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Unearned voluntary protection contract revenues and insurance earned premiums.

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For an unclassified balance sheet, amount of receivables arising from transactions with related parties.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Unsecured short-term debt instrument issued by corporations which are highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

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Amount receivable from related parties classified as other.

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Amount payable to related parties classified as other.

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The amount for notes payable (written promise to pay), due to related parties.

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For an unclassified balance sheet, amounts due from parties associated with the reporting entity as evidenced by a written promise to pay.

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