Variable Interest Entities - Schedule of Assets and Liabilities related to Variable Interest Entities Securitization Transactions (Details) - USD ($) $ in Millions	Jun. 30, 2020	Mar. 31, 2020
Variable Interest Entity [Line Items]
Restricted Cash	$ 1,798	$ 1,739
Net Securitized Assets	71,117	73,996
Other Assets	2,955	2,823
Debt	106,969	97,740
Other liabilities	7,976	7,854
Other assets [Member]
Variable Interest Entity [Line Items]
Restricted Cash	1,329	996
Net Securitized Assets	22,880	17,961
Other Assets	156	131
Other liabilities [Member]
Variable Interest Entity [Line Items]
Debt	18,939	14,568
Other liabilities	12	12
Retail Finance Receivables [Member] | Other assets [Member]
Variable Interest Entity [Line Items]
Restricted Cash	973	694
Net Securitized Assets	16,194	12,375
Other Assets	35	5
Retail Finance Receivables [Member] | Other liabilities [Member]
Variable Interest Entity [Line Items]
Debt	14,500	10,933
Other liabilities	11	10
Investments In Operating Leases, Net [Member] | Other assets [Member]
Variable Interest Entity [Line Items]
Restricted Cash	356	302
Net Securitized Assets	6,686	5,586
Other Assets	121	126
Investments In Operating Leases, Net [Member] | Other liabilities [Member]
Variable Interest Entity [Line Items]
Debt	4,439	3,635
Other liabilities	$ 1	$ 2