Finance Receivables, Net - Schedule of Amortized Cost Basis of Retail Loan Portfolio and Dealer Products Portfolio by Credit Quality Indicator (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2024	Mar. 31, 2024
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	$ 2,147	$ 2,147	$ 2,083
Year two, originated, fiscal year before current fiscal year	1,584	1,584	1,381
Year three, originated, two years before current fiscal year	732	732	1,117
Year four, originated, three years before current fiscal year	771	771	1,026
Year five, originated, four years before current fiscal year	899	899	235
Originated, more than five years before current fiscal year	890	890	945
Revolving loans	9,803	9,803	9,394
Total	16,826	16,826	16,181
Gross Charge-Offs, Total	0	0	0
Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	26,483	26,483	35,823
Year two, originated, fiscal year before current fiscal year	27,510	27,510	23,173
Year three, originated, two years before current fiscal year	16,865	16,865	15,639
Year four, originated, three years before current fiscal year	10,915	10,915	8,878
Year five, originated, four years before current fiscal year	5,345	5,345	2,783
Originated, more than five years before current fiscal year	1,473	1,473	829
Total	88,591	88,591	87,125
Gross Charge-Offs, year one, originated, current fiscal year		8	38
Gross Charge-Offs, Year two, originated, fiscal year before current fiscal year		181	297
Gross Charge-Offs, Year three, originated, two years before current fiscal year		238	258
Gross Charge-Offs, Year four, originated, three years before current fiscal year		150	111
Gross Charge-Offs, Year five, originated, four years before current fiscal year		58	38
Gross Charge-Offs, Originated, more than five years before current fiscal year		31	34
Gross Charge-Offs, Total		666	776
Current [Member] | Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	26,248	26,248	35,407
Year two, originated, fiscal year before current fiscal year	26,863	26,863	22,473
Year three, originated, two years before current fiscal year	16,166	16,166	15,041
Year four, originated, three years before current fiscal year	10,376	10,376	8,539
Year five, originated, four years before current fiscal year	5,061	5,061	2,654
Originated, more than five years before current fiscal year	1,348	1,348	748
Total	86,062	86,062	84,862
30-59 Days Past Due [Member] | Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	170	170	301
Year two, originated, fiscal year before current fiscal year	455	455	488
Year three, originated, two years before current fiscal year	485	485	426
Year four, originated, three years before current fiscal year	382	382	242
Year five, originated, four years before current fiscal year	201	201	92
Originated, more than five years before current fiscal year	84	84	53
Total	1,777	1,777	1,602
60-89 Days Past Due [Member] | Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	45	45	77
Year two, originated, fiscal year before current fiscal year	130	130	143
Year three, originated, two years before current fiscal year	146	146	119
Year four, originated, three years before current fiscal year	109	109	68
Year five, originated, four years before current fiscal year	58	58	27
Originated, more than five years before current fiscal year	26	26	17
Total	514	514	451
90 Days or Greater Past Due [Member] | Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	20	20	38
Year two, originated, fiscal year before current fiscal year	62	62	69
Year three, originated, two years before current fiscal year	68	68	53
Year four, originated, three years before current fiscal year	48	48	29
Year five, originated, four years before current fiscal year	25	25	10
Originated, more than five years before current fiscal year	15	15	11
Total	238	238	210
Wholesale [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	0	0
Year two, originated, fiscal year before current fiscal year	0	0	0
Year three, originated, two years before current fiscal year	0	0	0
Year four, originated, three years before current fiscal year	0	0	0
Year five, originated, four years before current fiscal year	0	0	0
Originated, more than five years before current fiscal year	0	0	0
Revolving loans	6,545	6,545	6,673
Total	6,545	6,545	6,673
Wholesale [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	0	0
Year two, originated, fiscal year before current fiscal year	0	0	0
Year three, originated, two years before current fiscal year	0	0	0
Year four, originated, three years before current fiscal year	0	0	0
Year five, originated, four years before current fiscal year	0	0	0
Originated, more than five years before current fiscal year	0	0	0
Revolving loans	6,075	6,075	6,287
Total	6,075	6,075	6,287
Wholesale [Member] | Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	0	0
Year two, originated, fiscal year before current fiscal year	0	0	0
Year three, originated, two years before current fiscal year	0	0	0
Year four, originated, three years before current fiscal year	0	0	0
Year five, originated, four years before current fiscal year	0	0	0
Originated, more than five years before current fiscal year	0	0	0
Revolving loans	431	431	238
Total	431	431	238
Wholesale [Member] | At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	0	0
Year two, originated, fiscal year before current fiscal year	0	0	0
Year three, originated, two years before current fiscal year	0	0	0
Year four, originated, three years before current fiscal year	0	0	0
Year five, originated, four years before current fiscal year	0	0	0
Originated, more than five years before current fiscal year	0	0	0
Revolving loans	39	39	112
Total	39	39	112
Wholesale [Member] | Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	0	0
Year two, originated, fiscal year before current fiscal year	0	0	0
Year three, originated, two years before current fiscal year	0	0	0
Year four, originated, three years before current fiscal year	0	0	0
Year five, originated, four years before current fiscal year	0	0	0
Originated, more than five years before current fiscal year	0	0	0
Revolving loans	0	0	36
Total	0	0	36
Real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	1,430	1,430	1,294
Year two, originated, fiscal year before current fiscal year	1,027	1,027	923
Year three, originated, two years before current fiscal year	499	499	869
Year four, originated, three years before current fiscal year	605	605	891
Year five, originated, four years before current fiscal year	791	791	128
Originated, more than five years before current fiscal year	697	697	786
Revolving loans	153	153	3
Total	5,202	5,202	4,894
Real estate [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	1,375	1,375	1,224
Year two, originated, fiscal year before current fiscal year	955	955	883
Year three, originated, two years before current fiscal year	489	489	815
Year four, originated, three years before current fiscal year	581	581	860
Year five, originated, four years before current fiscal year	789	789	128
Originated, more than five years before current fiscal year	697	697	784
Revolving loans	153	153	3
Total	5,039	5,039	4,697
Real estate [Member] | Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	50	50	58
Year two, originated, fiscal year before current fiscal year	65	65	37
Year three, originated, two years before current fiscal year	10	10	44
Year four, originated, three years before current fiscal year	24	24	6
Year five, originated, four years before current fiscal year	2	2	0
Originated, more than five years before current fiscal year	0	0	0
Revolving loans	0	0	0
Total	151	151	145
Real estate [Member] | At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	5	5	8
Year two, originated, fiscal year before current fiscal year	7	7	1
Year three, originated, two years before current fiscal year	0	0	10
Year four, originated, three years before current fiscal year	0	0	0
Year five, originated, four years before current fiscal year	0	0	0
Originated, more than five years before current fiscal year	0	0	2
Revolving loans	0	0	0
Total	12	12	21
Real estate [Member] | Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	0	4
Year two, originated, fiscal year before current fiscal year	0	0	2
Year three, originated, two years before current fiscal year	0	0	0
Year four, originated, three years before current fiscal year	0	0	25
Year five, originated, four years before current fiscal year	0	0	0
Originated, more than five years before current fiscal year	0	0	0
Revolving loans	0	0	0
Total	0	0	31
Working capital [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	717	717	789
Year two, originated, fiscal year before current fiscal year	557	557	458
Year three, originated, two years before current fiscal year	233	233	248
Year four, originated, three years before current fiscal year	166	166	135
Year five, originated, four years before current fiscal year	108	108	107
Originated, more than five years before current fiscal year	193	193	159
Revolving loans	3,105	3,105	2,718
Total	5,079	5,079	4,614
Working capital [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	713	713	769
Year two, originated, fiscal year before current fiscal year	542	542	414
Year three, originated, two years before current fiscal year	214	214	235
Year four, originated, three years before current fiscal year	163	163	122
Year five, originated, four years before current fiscal year	108	108	105
Originated, more than five years before current fiscal year	193	193	159
Revolving loans	3,103	3,103	2,715
Total	5,036	5,036	4,519
Working capital [Member] | Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	4	4	20
Year two, originated, fiscal year before current fiscal year	8	8	41
Year three, originated, two years before current fiscal year	19	19	13
Year four, originated, three years before current fiscal year	3	3	0
Year five, originated, four years before current fiscal year	0	0	0
Originated, more than five years before current fiscal year	0	0	0
Revolving loans	2	2	2
Total	36	36	76
Working capital [Member] | At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	0	0
Year two, originated, fiscal year before current fiscal year	7	7	3
Year three, originated, two years before current fiscal year	0	0	0
Year four, originated, three years before current fiscal year	0	0	0
Year five, originated, four years before current fiscal year	0	0	2
Originated, more than five years before current fiscal year	0	0	0
Revolving loans	0	0	1
Total	7	7	6
Working capital [Member] | Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	0	0
Year two, originated, fiscal year before current fiscal year	0	0	0
Year three, originated, two years before current fiscal year	0	0	0
Year four, originated, three years before current fiscal year	0	0	13
Year five, originated, four years before current fiscal year	0	0	0
Originated, more than five years before current fiscal year	0	0	0
Revolving loans	0	0	0
Total	$ 0	$ 0	$ 13