Related Party Transactions - Related Party Transactions Included in Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2024	Mar. 31, 2024
Cash and cash equivalents
Cash and cash equivalents	$ 8,284	$ 8,570
Investments in marketable securities
Investments in marketable securities	4,687	4,505
Other assets
Notes receivable	103,771	101,669
Other liabilities
Other payables, net	7,194	6,707
TMCC-affiliated companies [Member]
Finance receivables, net
Accounts receivable	90	49
Deferred retail subvention income	(1,130)	(953)
Investments in operating leases, net
Investments in operating leases, net	(99)	(80)
Deferred lease subvention income	(482)	(323)
Other assets
Notes receivable	2,113	1,724
Other receivables, net	77	86
Other liabilities
Unearned voluntary protection contract revenues and insurance earned premiums	486	433
Other payables, net	746	771
Notes payable	0	8
Commercial paper [Member] \| TMCC-affiliated companies [Member]
Investments in marketable securities
Investments in marketable securities	$ 15	$ 0

Amount of deferred operating lease 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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Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business.

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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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Including the current and noncurrent portions, aggregate carrying amount of all types of notes payable, as of the balance sheet date, with initial maturities beyond one year or beyond the normal operating cycle, if longer.

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Amortized cost, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement and net investment in lease.

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Amount of liabilities classified as other.

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Amount due from parties in nontrade transactions, classified as other.

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