Variable Interest Entities - Schedule of Assets and Liabilities related to Variable Interest Entities Securitization Transactions (Details) - USD ($) $ in Millions	Mar. 31, 2017	Mar. 31, 2016
Variable Interest Entity [Line Items]
Restricted Cash	$ 1,087	$ 1,010
Net Securitized Assets	68,462	65,636
Other Assets	2,044	2,217
Debt	98,233	93,594
Other liabilities	3,952	3,585
Variable Interest Entities Assets [Member]
Variable Interest Entity [Line Items]
Restricted Cash	1,067	989
Gross Securitized Assets	19,573	17,707
Net Securitized Assets	17,753	16,634
Other Assets	87	84
Variable Interest Entities Liabilities [Member]
Variable Interest Entity [Line Items]
Debt	14,319	14,123
Other liabilities	6	5
Retail Finance Receivables [Member] | Variable Interest Entities Assets [Member]
Variable Interest Entity [Line Items]
Restricted Cash	856	853
Gross Securitized Assets	13,071	14,343
Net Securitized Assets	12,865	14,130
Other Assets	7	6
Retail Finance Receivables [Member] | Variable Interest Entities Liabilities [Member]
Variable Interest Entity [Line Items]
Debt	11,017	12,434
Other liabilities	5	4
Investments In Operating Leases, Net [Member] | Variable Interest Entities Assets [Member]
Variable Interest Entity [Line Items]
Restricted Cash	211	136
Gross Securitized Assets	6,502	3,364
Net Securitized Assets	4,888	2,504
Other Assets	80	78
Investments In Operating Leases, Net [Member] | Variable Interest Entities Liabilities [Member]
Variable Interest Entity [Line Items]
Debt	3,302	1,689
Other liabilities	$ 1	$ 1