Related Party Transactions - Related Party Transactions Included in Consolidated Statements of Income (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Voluntary protection contract revenues and insurance earned premiums:
Voluntary protection contract revenues and insurance earned premiums	$ 259	$ 249
Expenses:
Operating and administrative	406	384
TMCC-affiliated companies [Member]
Net financing revenues:
Manufacturer's subvention and other revenues	339	479
Depreciation on operating leases	22	(28)
Interest expense:
Credit support fees, interest and other expenses	23	24
Voluntary protection contract revenues and insurance earned premiums:
Voluntary protection contract revenues and insurance earned premiums	40	42
Investment and other income, net:
Interest and other income	(6)	3
Expenses:
Operating and administrative	$ 21	$ 21