Related Party Transactions - Related Party Transactions Included in Consolidated Statement of Income (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Net financing revenues:
Manufacturers’ subvention support and other revenues	$ 336	$ 317
Credit support fees incurred	(23)	(22)
Interest and other expenses paid to affiliates	(1)	(2)
Insurance earned premiums and contract revenues:
Affiliate insurance premiums and contract revenues	193	174
Investments and other income, net:
Interest earned on notes receivable from affiliates	2	1
Expenses:
Insurance losses and loss adjustment expenses	89	79
TMCC-affiliated companies [Member]
Insurance earned premiums and contract revenues:
Affiliate insurance premiums and contract revenues	34	32
Expenses:
Shared services charges and other expenses	11	14
Employee benefits expense	6	$ 8
Insurance losses and loss adjustment expenses	$ 1