Finance Receivables, Net - Schedule of Retail Loan Portfolio and Dealer Products Portfolio by Credit Quality Indicator (Details) - USD ($) $ in Millions	Dec. 31, 2020	Mar. 31, 2020
Financing Receivable, Recorded Investment [Line Items]
Current	$ 78,869	$ 73,936
Financing receivables, past due	1,093	1,025
Total Finance receivables	79,962	74,961
Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	63,657	56,064
Financing receivables, past due	1,093	1,024
Total Finance receivables	64,750	57,088
Wholesale [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	7,457	9,826
Financing receivables, past due	0	0
Total Finance receivables	7,457	9,826
Wholesale [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance receivables		8,750
Wholesale [Member] | Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance receivables		962
Wholesale [Member] | At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance receivables		92
Wholesale [Member] | Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance receivables		22
Real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	5,207	4,627
Financing receivables, past due	0	1
Total Finance receivables	5,207	4,628
Real estate [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance receivables		3,974
Real estate [Member] | Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance receivables		576
Real estate [Member] | At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance receivables		55
Real estate [Member] | Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance receivables		23
Working capital [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	2,548	3,419
Financing receivables, past due	0	0
Total Finance receivables	2,548	3,419
Working capital [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance receivables		3,132
Working capital [Member] | Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance receivables		195
Working capital [Member] | At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance receivables		92
Working capital [Member] | Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Finance receivables		0
30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	789	717
30-59 Days Past Due [Member] | Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	789	717
30-59 Days Past Due [Member] | Wholesale [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	0	0
30-59 Days Past Due [Member] | Real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	0	0
30-59 Days Past Due [Member] | Working capital [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	0	0
60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	219	203
60-89 Days Past Due [Member] | Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	219	203
60-89 Days Past Due [Member] | Wholesale [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	0	0
60-89 Days Past Due [Member] | Real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	0	0
60-89 Days Past Due [Member] | Working capital [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	0	0
90 Days or Greater Past Due [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	85	105
90 Days or Greater Past Due [Member] | Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	85	104
90 Days or Greater Past Due [Member] | Wholesale [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	0	0
90 Days or Greater Past Due [Member] | Real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	0	1
90 Days or Greater Past Due [Member] | Working capital [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivables, past due	$ 0	$ 0