Finance Receivables and Loans, Net - Schedule of Financing Receivable Credit Quality Indicators Commercial (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
Total finance receivables and loans	$ 137,501	$ 139,439
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	1,672	1,820
Year two, originated, fiscal year before current fiscal year	1,697	2,845
Year three, originated, two years before current fiscal year	2,451	1,929
Year four, originated, three years before current fiscal year	1,783	1,597
Year five, originated, four years before current fiscal year	1,294	1,002
Originated, more than five years before current fiscal year	1,674	1,223
Revolving loans	23,683	23,811
Revolving loans converted to term	152	235
Total finance receivables and loans	34,406	34,462
Automotive | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	400	515
Year two, originated, fiscal year before current fiscal year	346	520
Year three, originated, two years before current fiscal year	400	195
Year four, originated, three years before current fiscal year	158	98
Year five, originated, four years before current fiscal year	76	59
Originated, more than five years before current fiscal year	65	37
Revolving loans	17,814	17,276
Revolving loans converted to term	0	0
Total finance receivables and loans	19,259	18,700
Automotive | Pass | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	395	509
Year two, originated, fiscal year before current fiscal year	325	512
Year three, originated, two years before current fiscal year	386	165
Year four, originated, three years before current fiscal year	133	97
Year five, originated, four years before current fiscal year	74	58
Originated, more than five years before current fiscal year	57	22
Revolving loans	16,633	16,446
Revolving loans converted to term	0	0
Total finance receivables and loans	18,003	17,809
Automotive | Special mention | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	5	6
Year two, originated, fiscal year before current fiscal year	20	7
Year three, originated, two years before current fiscal year	14	30
Year four, originated, three years before current fiscal year	25	1
Year five, originated, four years before current fiscal year	2	1
Originated, more than five years before current fiscal year	8	14
Revolving loans	1,061	723
Revolving loans converted to term	0	0
Total finance receivables and loans	1,135	782
Automotive | Substandard | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	0	0
Year two, originated, fiscal year before current fiscal year	1	1
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	110	44
Revolving loans converted to term	0	0
Total finance receivables and loans	111	45
Automotive | Doubtful | Commercial
Financing Receivable, Credit Quality Indicator [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	1
Revolving loans	10	63
Revolving loans converted to term	0	0
Total finance receivables and loans	10	64
Other | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	526	331
Year two, originated, fiscal year before current fiscal year	325	854
Year three, originated, two years before current fiscal year	680	577
Year four, originated, three years before current fiscal year	525	614
Year five, originated, four years before current fiscal year	390	318
Originated, more than five years before current fiscal year	392	374
Revolving loans	5,869	6,435
Revolving loans converted to term	117	209
Total finance receivables and loans	8,824	9,712
Other | Pass | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	526	331
Year two, originated, fiscal year before current fiscal year	298	646
Year three, originated, two years before current fiscal year	313	343
Year four, originated, three years before current fiscal year	264	405
Year five, originated, four years before current fiscal year	172	266
Originated, more than five years before current fiscal year	235	180
Revolving loans	5,614	6,202
Revolving loans converted to term	91	173
Total finance receivables and loans	7,513	8,546
Other | Special mention | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	0	0
Year two, originated, fiscal year before current fiscal year	0	208
Year three, originated, two years before current fiscal year	367	188
Year four, originated, three years before current fiscal year	238	206
Year five, originated, four years before current fiscal year	172	51
Originated, more than five years before current fiscal year	77	85
Revolving loans	235	198
Revolving loans converted to term	23	25
Total finance receivables and loans	1,112	961
Other | Substandard | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	0	0
Year two, originated, fiscal year before current fiscal year	27	0
Year three, originated, two years before current fiscal year	0	46
Year four, originated, three years before current fiscal year	23	3
Year five, originated, four years before current fiscal year	46	0
Originated, more than five years before current fiscal year	54	83
Revolving loans	10	25
Revolving loans converted to term	3	11
Total finance receivables and loans	163	168
Other | Doubtful | Commercial
Financing Receivable, Credit Quality Indicator [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	26	26
Revolving loans	10	10
Revolving loans converted to term	0	0
Total finance receivables and loans	36	36
Other | Loss | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year		0
Year two, originated, fiscal year before current fiscal year		0
Year three, originated, two years before current fiscal year		0
Year four, originated, three years before current fiscal year		0
Year five, originated, four years before current fiscal year		1
Originated, more than five years before current fiscal year		0
Revolving loans		0
Revolving loans converted to term		0
Total finance receivables and loans		1
Commercial real estate | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	746	974
Year two, originated, fiscal year before current fiscal year	1,026	1,471
Year three, originated, two years before current fiscal year	1,371	1,157
Year four, originated, three years before current fiscal year	1,100	885
Year five, originated, four years before current fiscal year	828	625
Originated, more than five years before current fiscal year	1,217	812
Revolving loans	0	100
Revolving loans converted to term	35	26
Total finance receivables and loans	6,323	6,050
Commercial real estate | Pass | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	740	971
Year two, originated, fiscal year before current fiscal year	1,008	1,452
Year three, originated, two years before current fiscal year	1,296	1,129
Year four, originated, three years before current fiscal year	1,058	884
Year five, originated, four years before current fiscal year	825	607
Originated, more than five years before current fiscal year	1,216	811
Revolving loans	0	100
Revolving loans converted to term	35	26
Total finance receivables and loans	6,178	5,980
Commercial real estate | Special mention | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	6	3
Year two, originated, fiscal year before current fiscal year	18	16
Year three, originated, two years before current fiscal year	69	28
Year four, originated, three years before current fiscal year	42	1
Year five, originated, four years before current fiscal year	0	18
Originated, more than five years before current fiscal year	0	0
Revolving loans	0	0
Revolving loans converted to term	0	0
Total finance receivables and loans	135	66
Commercial real estate | Substandard | Commercial
Financing Receivable, Credit Quality Indicator [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	5	0
Year four, originated, three years before current fiscal year	0	0
Year five, originated, four years before current fiscal year	3	0
Originated, more than five years before current fiscal year	0	1
Revolving loans	0	0
Revolving loans converted to term	0	0
Total finance receivables and loans	8	$ 4
Commercial real estate | Doubtful | Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	0
Year two, originated, fiscal year before current fiscal year	0
Year three, originated, two years before current fiscal year	1
Year four, originated, three years before current fiscal year	0
Year five, originated, four years before current fiscal year	0
Originated, more than five years before current fiscal year	1
Revolving loans	0
Revolving loans converted to term	0
Total finance receivables and loans	$ 2