Related Party Transactions - Related Party Transactions Included in Consolidated Statements of Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2022	Dec. 31, 2021
Voluntary protection contract revenues and insurance earned premiums:
Voluntary protection contract revenues and insurance earned premiums	$ 263	$ 255	$ 785	$ 758
Expenses:
Operating and administrative	463	394	1,313	1,163
TMCC-affiliated companies [Member]
Net financing revenues:
Manufacturer's subvention and other revenues	300	425	955	1,361
Depreciation on operating leases	23	(14)	79	(67)
Interest expense:
Credit support fees, interest and other expenses	25	25	72	76
Voluntary protection contract revenues and insurance earned premiums:
Voluntary protection contract revenues and insurance earned premiums	39	42	118	127
Investment and other income, net:
Interest and other income	21	1	18	6
Expenses:
Operating and administrative	$ 42	$ 19	$ 79	$ 62