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	12 Months Ended
	Jun. 30, 2024	Mar. 31, 2024
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	$ 714	$ 2,083
Year two, originated, fiscal year before current fiscal year	1,900	1,381
Year three, originated, two years before current fiscal year	1,213	1,117
Year four, originated, three years before current fiscal year	1,011	1,026
Year five, originated, four years before current fiscal year	978	235
Originated, more than five years before current fiscal year	1,092	945
Revolving loans	9,666	9,394
Total	16,574	16,181
Gross Charge-Offs, Total	0	0
Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	9,868	35,823
Year two, originated, fiscal year before current fiscal year	33,343	23,173
Year three, originated, two years before current fiscal year	20,969	15,639
Year four, originated, three years before current fiscal year	13,973	8,878
Year five, originated, four years before current fiscal year	7,627	2,783
Originated, more than five years before current fiscal year	2,748	829
Total	88,528	87,125
Gross Charge-Offs, year one, originated, current fiscal year	0	38
Gross Charge-Offs, Year two, originated, fiscal year before current fiscal year	43	297
Gross Charge-Offs, Year three, originated, two years before current fiscal year	74	258
Gross Charge-Offs, Year four, originated, three years before current fiscal year	50	111
Gross Charge-Offs, Year five, originated, four years before current fiscal year	20	38
Gross Charge-Offs, Originated, more than five years before current fiscal year	11	34
Gross Charge-Offs, Total	198	776
Current [Member] | Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	9,847	35,407
Year two, originated, fiscal year before current fiscal year	32,739	22,473
Year three, originated, two years before current fiscal year	20,203	15,041
Year four, originated, three years before current fiscal year	13,348	8,539
Year five, originated, four years before current fiscal year	7,288	2,654
Originated, more than five years before current fiscal year	2,560	748
Total	85,985	84,862
30-59 Days Past Due [Member] | Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	21	301
Year two, originated, fiscal year before current fiscal year	420	488
Year three, originated, two years before current fiscal year	518	426
Year four, originated, three years before current fiscal year	433	242
Year five, originated, four years before current fiscal year	236	92
Originated, more than five years before current fiscal year	124	53
Total	1,752	1,602
60-89 Days Past Due [Member] | Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	77
Year two, originated, fiscal year before current fiscal year	133	143
Year three, originated, two years before current fiscal year	177	119
Year four, originated, three years before current fiscal year	141	68
Year five, originated, four years before current fiscal year	77	27
Originated, more than five years before current fiscal year	44	17
Total	572	451
90 Days or Greater Past Due [Member] | Retail Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	38
Year two, originated, fiscal year before current fiscal year	51	69
Year three, originated, two years before current fiscal year	71	53
Year four, originated, three years before current fiscal year	51	29
Year five, originated, four years before current fiscal year	26	10
Originated, more than five years before current fiscal year	20	11
Total	219	210
Wholesale [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	0
Year two, originated, fiscal year before current fiscal year	0	0
Year three, originated, two years before current fiscal year	0	0
Year four, originated, three years before current fiscal year	0	0
Year five, originated, four years before current fiscal year	0	0
Originated, more than five years before current fiscal year	0	0
Revolving loans	6,608	6,673
Total	6,608	6,673
Wholesale [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	0
Year two, originated, fiscal year before current fiscal year	0	0
Year three, originated, two years before current fiscal year	0	0
Year four, originated, three years before current fiscal year	0	0
Year five, originated, four years before current fiscal year	0	0
Originated, more than five years before current fiscal year	0	0
Revolving loans	6,183	6,287
Total	6,183	6,287
Wholesale [Member] | Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	0
Year two, originated, fiscal year before current fiscal year	0	0
Year three, originated, two years before current fiscal year	0	0
Year four, originated, three years before current fiscal year	0	0
Year five, originated, four years before current fiscal year	0	0
Originated, more than five years before current fiscal year	0	0
Revolving loans	290	238
Total	290	238
Wholesale [Member] | At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	0
Year two, originated, fiscal year before current fiscal year	0	0
Year three, originated, two years before current fiscal year	0	0
Year four, originated, three years before current fiscal year	0	0
Year five, originated, four years before current fiscal year	0	0
Originated, more than five years before current fiscal year	0	0
Revolving loans	99	112
Total	99	112
Wholesale [Member] | Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	0
Year two, originated, fiscal year before current fiscal year	0	0
Year three, originated, two years before current fiscal year	0	0
Year four, originated, three years before current fiscal year	0	0
Year five, originated, four years before current fiscal year	0	0
Originated, more than five years before current fiscal year	0	0
Revolving loans	36	36
Total	36	36
Real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	457	1,294
Year two, originated, fiscal year before current fiscal year	1,184	923
Year three, originated, two years before current fiscal year	903	869
Year four, originated, three years before current fiscal year	783	891
Year five, originated, four years before current fiscal year	849	128
Originated, more than five years before current fiscal year	836	786
Revolving loans	81	3
Total	5,093	4,894
Real estate [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	397	1,224
Year two, originated, fiscal year before current fiscal year	1,115	883
Year three, originated, two years before current fiscal year	901	815
Year four, originated, three years before current fiscal year	755	860
Year five, originated, four years before current fiscal year	811	128
Originated, more than five years before current fiscal year	828	784
Revolving loans	81	3
Total	4,888	4,697
Real estate [Member] | Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	55	58
Year two, originated, fiscal year before current fiscal year	60	37
Year three, originated, two years before current fiscal year	0	44
Year four, originated, three years before current fiscal year	21	6
Year five, originated, four years before current fiscal year	14	0
Originated, more than five years before current fiscal year	6	0
Revolving loans	0	0
Total	156	145
Real estate [Member] | At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	8
Year two, originated, fiscal year before current fiscal year	9	1
Year three, originated, two years before current fiscal year	0	10
Year four, originated, three years before current fiscal year	7	0
Year five, originated, four years before current fiscal year	0	0
Originated, more than five years before current fiscal year	2	2
Revolving loans	0	0
Total	18	21
Real estate [Member] | Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	5	4
Year two, originated, fiscal year before current fiscal year	0	2
Year three, originated, two years before current fiscal year	2	0
Year four, originated, three years before current fiscal year	0	25
Year five, originated, four years before current fiscal year	24	0
Originated, more than five years before current fiscal year	0	0
Revolving loans	0	0
Total	31	31
Working capital [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	257	789
Year two, originated, fiscal year before current fiscal year	716	458
Year three, originated, two years before current fiscal year	310	248
Year four, originated, three years before current fiscal year	228	135
Year five, originated, four years before current fiscal year	129	107
Originated, more than five years before current fiscal year	256	159
Revolving loans	2,977	2,718
Total	4,873	4,614
Working capital [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	247	769
Year two, originated, fiscal year before current fiscal year	702	414
Year three, originated, two years before current fiscal year	292	235
Year four, originated, three years before current fiscal year	222	122
Year five, originated, four years before current fiscal year	116	105
Originated, more than five years before current fiscal year	256	159
Revolving loans	2,973	2,715
Total	4,808	4,519
Working capital [Member] | Credit Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	10	20
Year two, originated, fiscal year before current fiscal year	14	41
Year three, originated, two years before current fiscal year	15	13
Year four, originated, three years before current fiscal year	6	0
Year five, originated, four years before current fiscal year	0	0
Originated, more than five years before current fiscal year	0	0
Revolving loans	3	2
Total	48	76
Working capital [Member] | At Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	0
Year two, originated, fiscal year before current fiscal year	0	3
Year three, originated, two years before current fiscal year	3	0
Year four, originated, three years before current fiscal year	0	0
Year five, originated, four years before current fiscal year	0	2
Originated, more than five years before current fiscal year	0	0
Revolving loans	1	1
Total	4	6
Working capital [Member] | Default [Member]
Financing Receivable, Recorded Investment [Line Items]
Year one, originated, current fiscal year	0	0
Year two, originated, fiscal year before current fiscal year	0	0
Year three, originated, two years before current fiscal year	0	0
Year four, originated, three years before current fiscal year	0	13
Year five, originated, four years before current fiscal year	13	0
Originated, more than five years before current fiscal year	0	0
Revolving loans	0	0
Total	$ 13	$ 13