Finance Receivables, Net - Net Financing Receivables (Details) - USD ($) $ in Millions	Dec. 31, 2021	Mar. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross finance receivables	$ 82,110	$ 80,370
Allowance for credit losses	(1,185)	(1,178)
Finance receivables, net	80,925	79,192
Finance Receivables, Net [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross finance receivables	81,981	80,633
Deferred origination costs	1,305	1,145
Deferred income	(1,176)	(1,408)
Allowance for credit losses	(1,185)	(1,178)
Finance receivables, net	80,925	79,192
Finance Receivables, Net [Member] | Retail receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross finance receivables	71,727	66,991
Allowance for credit losses	(1,140)	(1,075)
Finance Receivables, Net [Member] | Dealer financing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross finance receivables	10,254	13,642
Allowance for credit losses	$ (45)	$ (103)