Loans and Related Allowance for Credit Losses (Credit Quality Indicators for Automobile, Credit Card, Education and Other Consumer Loan Classes) (Details) - USD ($) $ in Millions		Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net	[1]	$ 326,025	$ 288,372
Automobile | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		5,139	6,612
Year two		4,424	3,403
Year three		2,054	3,765
Year four		2,067	1,874
Year five		878	738
Prior		274	243
Total loans, net		14,836	16,635
Automobile | FICO Score, Greater Than Or Equal To 780 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		2,390	3,247
Year two		2,162	1,496
Year three		922	1,380
Year four		760	533
Year five		241	226
Prior		75	79
Total loans, net		6,550	6,961
Automobile | FICO Score, 720 to 779 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		1,702	2,119
Year two		1,312	983
Year three		561	1,030
Year four		538	499
Year five		222	195
Prior		69	62
Total loans, net		4,404	4,888
Automobile | FICO Score, 660 to 719 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		854	969
Year two		660	609
Year three		341	772
Year four		401	413
Year five		187	155
Prior		56	44
Total loans, net		2,499	2,962
Automobile | FICO Score, Less Than 660 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		193	277
Year two		290	315
Year three		230	583
Year four		368	429
Year five		228	162
Prior		74	58
Total loans, net		1,383	1,824
Credit card | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		7,010	6,564
Revolving Loans Converted to Term		59	62
Total loans, net		7,069	6,626
Credit card | FICO Score, Greater Than Or Equal To 780 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		1,954	1,815
Revolving Loans Converted to Term		2	2
Total loans, net		1,956	1,817
Credit card | FICO Score, 720 to 779 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		1,994	1,836
Revolving Loans Converted to Term		6	9
Total loans, net		2,000	1,845
Credit card | FICO Score, 660 to 719 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		1,957	1,856
Revolving Loans Converted to Term		13	19
Total loans, net		1,970	1,875
Credit card | FICO Score, Less Than 660 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		1,001	943
Revolving Loans Converted to Term		35	29
Total loans, net		1,036	972
Credit card | No FICO Score Available Or Required | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		104	114
Revolving Loans Converted to Term		3	3
Total loans, net		107	117
Education
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		126	76
Year two		97	109
Year three		88	134
Year four		105	107
Year five		85	78
Prior		1,672	2,029
Total loans, net		2,173	2,533
Education | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		126	76
Year two		97	109
Year three		88	134
Year four		105	107
Year five		85	78
Prior		584	651
Total loans, net		1,085	1,155
Education | FICO Score, Greater Than Or Equal To 780 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		42	37
Year two		53	60
Year three		48	77
Year four		61	62
Year five		51	48
Prior		357	392
Total loans, net		612	676
Education | FICO Score, 720 to 779 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		39	20
Year two		27	29
Year three		24	37
Year four		30	30
Year five		24	21
Prior		143	160
Total loans, net		287	297
Education | FICO Score, 660 to 719 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		21	7
Year two		8	9
Year three		8	11
Year four		9	11
Year five		8	7
Prior		59	73
Total loans, net		113	118
Education | FICO Score, Less Than 660 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		4	1
Year two		1	1
Year three		1	2
Year four		2	2
Year five		2	2
Prior		24	25
Total loans, net		34	33
Education | No FICO Score Available Or Required | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		20	11
Year two		8	10
Year three		7	7
Year four		3	2
Year five
Prior		1	1
Total loans, net		39	31
Education | Other Internal Credit Metrics
Financing Receivable, Credit Quality Indicator [Line Items]
Prior		1,088	1,378
Total loans, net		1,088	1,378
Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		912	776
Year two		420	541
Year three		266	575
Year four		248	274
Year five		89	75
Prior		76	116
Revolving Loans		2,995	3,347
Revolving Loans Converted to Term		20	23
Total loans, net		5,026	5,727
Other consumer | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		787	689
Year two		377	510
Year three		226	540
Year four		214	251
Year five		82	53
Prior		47	68
Revolving Loans		275	392
Revolving Loans Converted to Term		8	2
Total loans, net		2,016	2,505
Other consumer | FICO Score, Greater Than Or Equal To 780 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		224	199
Year two		97	131
Year three		53	123
Year four		46	47
Year five		14	12
Prior		18	32
Revolving Loans		47	95
Revolving Loans Converted to Term		2	1
Total loans, net		501	640
Other consumer | FICO Score, 720 to 779 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		302	250
Year two		122	172
Year three		68	167
Year four		62	68
Year five		20	15
Prior		15	19
Revolving Loans		89	125
Revolving Loans Converted to Term		2
Total loans, net		680	816
Other consumer | FICO Score, 660 to 719 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		229	190
Year two		110	145
Year three		68	165
Year four		66	82
Year five		28	16
Prior		8	11
Revolving Loans		95	122
Revolving Loans Converted to Term		2
Total loans, net		606	731
Other consumer | FICO Score, Less Than 660 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		32	50
Year two		48	62
Year three		37	85
Year four		40	54
Year five		20	10
Prior		6	6
Revolving Loans		44	50
Revolving Loans Converted to Term		2	1
Total loans, net		229	318
Other consumer | Other Internal Credit Metrics
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		125	87
Year two		43	31
Year three		40	35
Year four		34	23
Year five		7	22
Prior		29	48
Revolving Loans		2,720	2,955
Revolving Loans Converted to Term		12	21
Total loans, net		$ 3,010	$ 3,222

[1] Our consolidated assets included the following for which we have elected the fair value option: Loans held for sale of $0.9 billion, Loans of $1.3 billion and Other assets of $0.1 billion at December 31, 2022 and Loans held for sale of $1.9 billion, Loans of $1.5 billion and Other assets of $0.1 billion at December 31, 2021.