Allowance for Credit Losses - Allowance for Credit Losses and Finance Receivables by Portfolio Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Financing Receivable Allowance For Credit Losses [Abstract]
Provision for credit losses			$ 291	$ 65
Finance Receivables, Net [Member]
Financing Receivable Allowance For Credit Losses [Abstract]
Allowance for credit losses at beginning of period	$ 1,274	$ 1,196	1,272	1,215
Charge-offs	(106)	(55)	(197)	(88)
Recoveries	14	15	29	32
Provision for credit losses	213	68	291	65
Allowance for credit losses at end of period	1,395	1,224	1,395	1,224
Finance Receivables, Net [Member] | Dealer products [Member]
Financing Receivable Allowance For Credit Losses [Abstract]
Allowance for credit losses at beginning of period	65	144	77	140
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision for credit losses	9	(55)	(3)	(51)
Allowance for credit losses at end of period	74	89	74	89
Finance Receivables, Net [Member] | Retail loan [Member]
Financing Receivable Allowance For Credit Losses [Abstract]
Allowance for credit losses at beginning of period	1,209	1,052	1,195	1,075
Charge-offs	(106)	(55)	(197)	(88)
Recoveries	14	15	29	32
Provision for credit losses	204	123	294	116
Allowance for credit losses at end of period	$ 1,321	$ 1,135	$ 1,321	$ 1,135