Allowance for Credit Losses - Allowance for Credit Losses and Finance Receivables by Portfolio Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2023		Mar. 31, 2022		Mar. 31, 2021
Financing Receivable Allowance For Credit Losses [Abstract]
Provision for credit losses	$ 713		$ 236		$ 426
Finance Receivables, Net [Member]
Financing Receivable Allowance For Credit Losses [Abstract]
Allowance for credit losses at beginning of period	1,272	[1]	1,215
Charge-offs	(535)		(237)
Recoveries	63		58
Provision for credit losses	713		236
Allowance for credit losses at end of period	1,513	[2]	1,272	[1]	1,215
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]	1,075
Charge-offs	(535)		(237)
Recoveries	63		58
Provision for credit losses	707		299
Allowance for credit losses at end of period	1,430	[2]	1,195	[1]	1,075
Finance Receivables, Net [Member] | Dealer products [Member]
Financing Receivable Allowance For Credit Losses [Abstract]
Allowance for credit losses at beginning of period	77	[1]	140
Charge-offs	0		0
Recoveries	0		0
Provision for credit losses	6		(63)
Allowance for credit losses at end of period	$ 83	[2]	$ 77	[1]	$ 140

[1] Ending balance includes $26 million of allowance for credit losses recorded in Other liabilities on the Consolidated Balance Sheet which is related to off-balance sheet commitments in the dealer products portfolio.

[2] Ending balance includes $24 million of allowance for credit losses recorded in Other liabilities on the Consolidated Balance Sheet which is related to off-balance sheet commitments in the dealer products portfolio.