Related Party Transactions - Related Party Transactions Included in Consolidated Statements of Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Net financing revenues:
Depreciation on operating leases	$ (1,460)	$ (1,450)	$ (4,400)	$ (4,484)
Voluntary protection contract revenues and insurance earned premiums:
Voluntary protection contract revenues and insurance earned premiums	255	241	758	714
Expenses:
Operating and administrative expenses	394	354	1,163	1,088
TMCC-affiliated companies [Member]
Net financing revenues:
Manufacturer's subvention and other revenues	425	503	1,361	1,504
Depreciation on operating leases	(14)	(33)	(67)	(82)
Interest expense:
Credit support fees, interest and other expenses	25	26	76	93
Voluntary protection contract revenues and insurance earned premiums:
Voluntary protection contract revenues and insurance earned premiums	42	43	127	130
Investment and other income, net:
Interest and other income	1	3	6	16
Expenses:
Operating and administrative expenses	$ 19	$ 20	$ 62	$ 63