Loans and Related Allowance for Credit Losses (Credit Quality Indicators for Automobile, Credit Card, Education and Other Consumer Loan Classes) (Details) - USD ($) $ in Millions		Sep. 30, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net	[1]	$ 315,400	$ 288,372
Automobile | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		4,000	6,612
Year two		4,847	3,403
Year three		2,320	3,765
Year four		2,396	1,874
Year five		1,073	738
Prior		389	243
Total loans, net		15,025	16,635
Automobile | Greater than or equal to 780 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		1,984	3,247
Year two		2,327	1,496
Year three		1,041	1,380
Year four		887	533
Year five		301	226
Prior		111	79
Total loans, net		6,651	6,961
Automobile | 720 to 779 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		1,277	2,119
Year two		1,503	983
Year three		649	1,030
Year four		635	499
Year five		277	195
Prior		100	62
Total loans, net		4,441	4,888
Automobile | 660 to 719 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		622	969
Year two		728	609
Year three		388	772
Year four		470	413
Year five		229	155
Prior		79	44
Total loans, net		2,516	2,962
Automobile | Less than 660 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		117	277
Year two		289	315
Year three		242	583
Year four		404	429
Year five		266	162
Prior		99	58
Total loans, net		1,417	1,824
Credit card | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		6,715	6,564
Revolving Loans Converted to Term		59	62
Total loans, net		6,774	6,626
Credit card | Greater than or equal to 780 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		1,835	1,815
Revolving Loans Converted to Term		2	2
Total loans, net		1,837	1,817
Credit card | 720 to 779 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		1,945	1,836
Revolving Loans Converted to Term		7	9
Total loans, net		1,952	1,845
Credit card | 660 to 719 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		1,876	1,856
Revolving Loans Converted to Term		15	19
Total loans, net		1,891	1,875
Credit card | Less than 660 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		952	943
Revolving Loans Converted to Term		32	29
Total loans, net		984	972
Credit card | No FICO score available or required | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		107	114
Revolving Loans Converted to Term		3	3
Total loans, net		110	117
Education
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		68	76
Year two		100	109
Year three		94	134
Year four		112	107
Year five		90	78
Prior		1,823	2,029
Total loans, net		2,287	2,533
Education | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		68	76
Year two		100	109
Year three		94	134
Year four		112	107
Year five		90	78
Prior		611	651
Total loans, net		1,075	1,155
Education | Greater than or equal to 780 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		18	37
Year two		55	60
Year three		51	77
Year four		63	62
Year five		52	48
Prior		373	392
Total loans, net		612	676
Education | 720 to 779 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		20	20
Year two		28	29
Year three		25	37
Year four		31	30
Year five		25	21
Prior		151	160
Total loans, net		280	297
Education | 660 to 719 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		12	7
Year two		8	9
Year three		8	11
Year four		10	11
Year five		9	7
Prior		64	73
Total loans, net		111	118
Education | Less than 660 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		2	1
Year two		1	1
Year three		1	2
Year four		2	2
Year five		2	2
Prior		22	25
Total loans, net		30	33
Education | No FICO score available or required | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		16	11
Year two		8	10
Year three		9	7
Year four		6	2
Year five		2
Prior		1	1
Total loans, net		42	31
Education | Other internal credit metrics
Financing Receivable, Credit Quality Indicator [Line Items]
Prior		1,212	1,378
Total loans, net		1,212	1,378
Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		691	776
Year two		482	541
Year three		316	575
Year four		329	274
Year five		119	75
Prior		87	116
Revolving Loans		3,235	3,347
Revolving Loans Converted to Term		34	23
Total loans, net		5,293	5,727
Other consumer | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		613	689
Year two		438	510
Year three		277	540
Year four		270	251
Year five		111	53
Prior		56	68
Revolving Loans		285	392
Revolving Loans Converted to Term		9	2
Total loans, net		2,059	2,505
Other consumer | Greater than or equal to 780 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		176	199
Year two		118	131
Year three		68	123
Year four		59	47
Year five		20	12
Prior		22	32
Revolving Loans		51	95
Revolving Loans Converted to Term		2	1
Total loans, net		516	640
Other consumer | 720 to 779 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		240	250
Year two		149	172
Year three		84	167
Year four		80	68
Year five		28	15
Prior		16	19
Revolving Loans		93	125
Revolving Loans Converted to Term		2
Total loans, net		692	816
Other consumer | 660 to 719 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		182	190
Year two		122	145
Year three		83	165
Year four		83	82
Year five		37	16
Prior		11	11
Revolving Loans		96	122
Revolving Loans Converted to Term		3
Total loans, net		617	731
Other consumer | Less than 660 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		15	50
Year two		49	62
Year three		42	85
Year four		48	54
Year five		26	10
Prior		7	6
Revolving Loans		45	50
Revolving Loans Converted to Term		2	1
Total loans, net		234	318
Other consumer | Other internal credit metrics
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		78	87
Year two		44	31
Year three		39	35
Year four		59	23
Year five		8	22
Prior		31	48
Revolving Loans		2,950	2,955
Revolving Loans Converted to Term		25	21
Total loans, net		$ 3,234	$ 3,222

[1] Our consolidated assets included the following for which we have elected the fair value option: Loans held for sale of $1.1 billion, Loans held for investment of $1.3 billion and Other assets of $0.1 billion at September 30, 2022. Comparable amounts at December 31, 2021 were $1.9 billion, $1.5 billion and $0.1 billion, respectively.