Related Party Transactions - Related Party Transactions Included in Consolidated Statements of Income (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Voluntary protection contract revenues and insurance earned premiums:
Voluntary protection contract revenues and insurance earned premiums	$ 271	$ 259
Expenses:
Operating and administrative	448	406
TMCC-affiliated companies [Member]
Net financing revenues:
Manufacturer's subvention and other revenues	270	339
Depreciation on operating leases	31	22
Interest expense:
Credit support fees, interest and other expenses	24	23
Voluntary protection contract revenues and insurance earned premiums:
Voluntary protection contract revenues and insurance earned premiums	38	40
Investment and other income, net:
Interest and other income	8	(6)
Expenses:
Operating and administrative	$ 24	$ 21