Related Party Transactions - Related Party Transactions Included in Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Mar. 31, 2023
Cash and cash equivalents
Cash and cash equivalents	$ 6,458	$ 6,398
Other assets
Finance receivables, net	100,884	90,280
Other liabilities
Other payables, net	6,760	5,674
TMCC-affiliated companies [Member]
Finance receivables, net
Accounts receivable	54	47
Deferred retail subvention income	(923)	(922)
Investments in operating leases, net
Investments in operating leases, net	(85)	(250)
Deferred lease subvention income	(287)	(410)
Other assets
Finance receivables, net	1,535	1,237
Other receivables, net	87	89
Other liabilities
Unearned voluntary protection contract revenues and insurance earned premiums	432	399
Other payables, net	818	432
Notes payable	8	8
Commercial paper [Member] | TMCC-affiliated companies [Member]
Cash and cash equivalents
Cash and cash equivalents	$ 0	$ 35