Variable Interest Entities - Schedule of Assets and Liabilities related to Variable Interest Entities Securitization Transactions (Details) - USD ($) $ in Millions	Dec. 31, 2023	Mar. 31, 2023
Variable Interest Entity [Line Items]
Restricted cash	$ 1,992	$ 2,090
Net securitized assets	100,884	90,280
Other assets	4,040	3,921
Debt	119,006	111,685
Other liabilities	6,760	5,674
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Restricted cash	1,992	2,090
Net securitized assets	29,762	28,764
Other assets	143	108
Debt	33,262	32,736
Other liabilities	62	51
Variable Interest Entity, Primary Beneficiary [Member] | Other assets [Member]
Variable Interest Entity [Line Items]
Net securitized assets	41,018	39,827
Other assets	143	108
Variable Interest Entity, Primary Beneficiary [Member] | Other liabilities [Member]
Variable Interest Entity [Line Items]
Debt	33,262	32,736
Other liabilities	62	51
Retail Finance Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Restricted cash	1,331	1,434
Retail Finance Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Other assets [Member]
Variable Interest Entity [Line Items]
Net securitized assets	29,762	28,764
Other assets	109	85
Retail Finance Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Other liabilities [Member]
Variable Interest Entity [Line Items]
Debt	25,837	25,155
Other liabilities	50	41
Investments In Operating Leases, Net [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Restricted cash	661	656
Investments In Operating Leases, Net [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Other assets [Member]
Variable Interest Entity [Line Items]
Net securitized assets	11,256	11,063
Other assets	34	23
Investments In Operating Leases, Net [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Other liabilities [Member]
Variable Interest Entity [Line Items]
Debt	7,425	7,581
Other liabilities	$ 12	$ 10