Finance Receivables, Net - Aging of Amortized Cost Basis of Finance Receivables by Class (Details) - USD ($) $ in Millions	Sep. 30, 2023	Mar. 31, 2023
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	$ 98,098	$ 91,769
90 Days or greater past due and accruing	146	111
30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	1,576	1,270
60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	457	378
90 Days or Greater Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	207	179
Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	2,240	1,827
Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	95,858	89,942
Retail Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	84,195	79,646
90 Days or greater past due and accruing	146	111
Retail Loan [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	1,576	1,270
Retail Loan [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	457	378
Retail Loan [Member] | 90 Days or Greater Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	207	179
Retail Loan [Member] | Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	2,240	1,827
Retail Loan [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	81,955	77,819
Wholesale [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	5,548	3,964
90 Days or greater past due and accruing	0	0
Wholesale [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	0	0
Wholesale [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	0	0
Wholesale [Member] | 90 Days or Greater Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	0	0
Wholesale [Member] | Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	0	0
Wholesale [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	5,548	3,964
Real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	4,866	4,975
90 Days or greater past due and accruing	0	0
Real estate [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	0	0
Real estate [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	0	0
Real estate [Member] | 90 Days or Greater Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	0	0
Real estate [Member] | Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	0	0
Real estate [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	4,866	4,975
Working capital [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	3,489	3,184
90 Days or greater past due and accruing	0	0
Working capital [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	0	0
Working capital [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	0	0
Working capital [Member] | 90 Days or Greater Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	0	0
Working capital [Member] | Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	0	0
Working capital [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Finance receivables	$ 3,489	$ 3,184