Related Party Transactions - Related Party Transactions Included in Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Jun. 30, 2024	Mar. 31, 2024
Cash and cash equivalents
Cash and cash equivalents	$ 5,967	$ 8,570
Other assets
Notes receivable	103,449	101,669
Other liabilities
Other payables, net	7,247	6,707
TMCC-affiliated companies [Member]
Finance receivables, net
Accounts receivable	88	49
Deferred retail subvention income	(1,024)	(953)
Investments in operating leases, net
Investments in operating leases, net	(88)	(80)
Deferred lease subvention income	(399)	(323)
Other assets
Notes receivable	1,662	1,724
Other receivables, net	74	86
Other liabilities
Unearned voluntary protection contract revenues and insurance earned premiums	438	433
Other payables, net	828	771
Notes payable	$ 8	$ 8