Allowance for Credit Losses - Allowance for Credit Losses and Finance Receivables by Portfolio Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Financing Receivable Allowance For Credit Losses [Abstract]
Provision for credit losses	$ 78	$ (3)
Finance Receivables, Net [Member]
Financing Receivable Allowance For Credit Losses [Abstract]
Allowance for credit losses at beginning of period	1,272	1,215
Charge-offs	(91)	(33)
Recoveries	15	17
Provision for credit losses	78	(3)
Allowance for credit losses at end of period	1,274	1,196
Finance Receivables, Net [Member] | Dealer products [Member]
Financing Receivable Allowance For Credit Losses [Abstract]
Allowance for credit losses at beginning of period	77	140
Charge-offs	0	0
Recoveries	0	0
Provision for credit losses	(12)	4
Allowance for credit losses at end of period	65	144
Finance Receivables, Net [Member] | Retail loan [Member]
Financing Receivable Allowance For Credit Losses [Abstract]
Allowance for credit losses at beginning of period	1,195	1,075
Charge-offs	(91)	(33)
Recoveries	15	17
Provision for credit losses	90	(7)
Allowance for credit losses at end of period	$ 1,209	$ 1,052