Related Party Transactions - Related Party Transactions Included in Consolidated Statements of Income (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Voluntary protection contract revenues and insurance earned premiums:
Voluntary protection contract revenues and insurance earned premiums	$ 1,053	$ 1,015	$ 956
Expenses:
Operating and administrative	1,776	1,697	1,487
TMCC-affiliated companies [Member]
Net financing revenues:
Manufacturer's subvention and other revenues	1,243	1,746	1,997
Depreciation on operating leases	106	(75)	(113)
Interest expense:
Credit support fees, interest and other expenses	96	99	117
Voluntary protection contract revenues and insurance earned premiums:
Voluntary protection contract revenues and insurance earned premiums	156	168	173
Investment and other income, net:
Interest and other income	35	3	18
Expenses:
Operating and administrative	$ 107	$ 82	$ 91