Related Party Transactions - Related Party Transactions Included in Consolidated Balance Sheet (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Mar. 31, 2016
Finance receivables, net
Accounts receivable from affiliates	$ 137	$ 119
Notes receivable under home loan programs	4	9
Deferred retail origination costs paid to affiliates	2	1
Deferred retail subvention income from affiliates	(944)	(794)
Investments in operating leases, net
Leases to affiliates	38,097	36,488
Deferred lease origination costs paid to affiliates	1	1
Deferred lease subvention income from affiliates	(1,134)	(1,057)
Other assets
Notes receivable from affiliates	889	1,177
Other receivables from affiliates, net	204	7
Other liabilities
Unearned insurance premiums and contract revenues	2,124	1,985
Other payables to affiliates, net	51	82
Notes payable to affiliates	13	20
TMCC-affiliated companies [Member]
Investments in operating leases, net
Leases to affiliates	3	2
Other liabilities
Unearned insurance premiums and contract revenues	325	278
Shareholder’s equity:
Stock-based compensation	2	2
TMCC-affiliated companies [Member] | Commercial paper [Member]
Cash and cash equivalents
Investments in affiliates' commercial paper	$ 15	$ 0