Allowance for Credit Losses - Allowance for Credit Losses and Finance Receivables by Portfolio Segment (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Dec. 31, 2023		Dec. 31, 2022		Dec. 31, 2023		Dec. 31, 2022
Financing Receivable Allowance For Credit Losses [Abstract]
Provision for credit losses					$ 592		$ 569
Retail loan [Member]
Financing Receivable Allowance For Credit Losses [Abstract]
Charge-offs					(536)
Finance Receivables, Net [Member]
Financing Receivable Allowance For Credit Losses [Abstract]
Allowance for credit losses at beginning of period	$ 1,628		$ 1,395		1,513		1,272
Charge-offs	(211)		(173)		(536)		(370)
Recoveries	27		13		81		42
Provision for credit losses	206		278		592		569
Allowance for credit losses at end of period	1,650	[1]	1,513	[2]	1,650	[1]	1,513	[2]
Finance Receivables, Net [Member] | Retail loan [Member]
Financing Receivable Allowance For Credit Losses [Abstract]
Allowance for credit losses at beginning of period	1,529		1,321		1,430		1,195
Charge-offs	(211)		(173)		(536)		(370)
Recoveries	27		13		81		42
Provision for credit losses	188		265		558		559
Allowance for credit losses at end of period	1,533	[1]	1,426	[2]	1,533	[1]	1,426	[2]
Finance Receivables, Net [Member] | Dealer products [Member]
Financing Receivable Allowance For Credit Losses [Abstract]
Allowance for credit losses at beginning of period	99		74		83		77
Charge-offs	0		0		0		0
Recoveries	0		0		0		0
Provision for credit losses	18		13		34		10
Allowance for credit losses at end of period	$ 117	[1]	$ 87	[2]	$ 117	[1]	$ 87	[2]

[1] Ending balance includes $45 million of allowance for credit losses recorded in Other liabilities on the Consolidated Balance Sheet which is related to off-balance sheet lending commitments in the dealer products portfolio.

[2] Ending balance includes $29 million of allowance for credit losses recorded in Other liabilities on the Consolidated Balance Sheet which is related to off-balance sheet lending commitments in the dealer products portfolio.