Loans and Related Allowance for Credit Losses (Credit Quality Indicators for Automobile, Credit Card, Education and Other Consumer Loan Classes) (Details) - USD ($) $ in Millions		Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net	[1]	$ 310,800	$ 288,372
Automobile | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		2,702	6,612
Year two		5,353	3,403
Year three		2,637	3,765
Year four		2,788	1,874
Year five		1,302	738
Prior		541	243
Total loans, net		15,323	16,635
Automobile | Greater than or equal to 780 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		1,391	3,247
Year two		2,543	1,496
Year three		1,186	1,380
Year four		1,032	533
Year five		371	226
Prior		161	79
Total loans, net		6,684	6,961
Automobile | 720 to 779 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		868	2,119
Year two		1,702	983
Year three		738	1,030
Year four		745	499
Year five		340	195
Prior		139	62
Total loans, net		4,532	4,888
Automobile | 660 to 719 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		392	969
Year two		817	609
Year three		446	772
Year four		552	413
Year five		278	155
Prior		109	44
Total loans, net		2,594	2,962
Automobile | Less than 660 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		51	277
Year two		291	315
Year three		267	583
Year four		459	429
Year five		313	162
Prior		132	58
Total loans, net		1,513	1,824
Credit card | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		6,588	6,564
Revolving Loans Converted to Term		62	62
Total loans, net		6,650	6,626
Credit card | Greater than or equal to 780 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		1,864	1,815
Revolving Loans Converted to Term		2	2
Total loans, net		1,866	1,817
Credit card | 720 to 779 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		1,912	1,836
Revolving Loans Converted to Term		8	9
Total loans, net		1,920	1,845
Credit card | 660 to 719 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		1,807	1,856
Revolving Loans Converted to Term		16	19
Total loans, net		1,823	1,875
Credit card | Less than 660 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		897	943
Revolving Loans Converted to Term		33	29
Total loans, net		930	972
Credit card | No FICO score available or required | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans		108	114
Revolving Loans Converted to Term		3	3
Total loans, net		111	117
Education
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		25	76
Year two		103	109
Year three		99	134
Year four		117	107
Year five		93	78
Prior		1,895	2,029
Total loans, net		2,332	2,533
Education | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		25	76
Year two		103	109
Year three		99	134
Year four		117	107
Year five		93	78
Prior		644	651
Total loans, net		1,081	1,155
Education | Greater than or equal to 780 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		10	37
Year two		58	60
Year three		54	77
Year four		67	62
Year five		55	48
Prior		391	392
Total loans, net		635	676
Education | 720 to 779 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		8	20
Year two		28	29
Year three		26	37
Year four		32	30
Year five		26	21
Prior		159	160
Total loans, net		279	297
Education | 660 to 719 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		3	7
Year two		7	9
Year three		8	11
Year four		10	11
Year five		9	7
Prior		68	73
Total loans, net		105	118
Education | Less than 660 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		1	1
Year two		2	1
Year three		2	2
Year four		2	2
Year five		2	2
Prior		25	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		3	11
Year two		8	10
Year three		9	7
Year four		6	2
Year five		1
Prior		1	1
Total loans, net		28	31
Education | Other internal credit metrics
Financing Receivable, Credit Quality Indicator [Line Items]
Prior		1,251	1,378
Total loans, net		1,251	1,378
Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		457	776
Year two		558	541
Year three		375	575
Year four		399	274
Year five		163	75
Prior		117	116
Revolving Loans		3,458	3,347
Revolving Loans Converted to Term		35	23
Total loans, net		5,562	5,727
Other consumer | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		397	689
Year two		512	510
Year three		340	540
Year four		341	251
Year five		148	53
Prior		73	68
Revolving Loans		300	392
Revolving Loans Converted to Term		8	2
Total loans, net		2,119	2,505
Other consumer | Greater than or equal to 780 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		116	199
Year two		144	131
Year three		86	123
Year four		76	47
Year five		28	12
Prior		28	32
Revolving Loans		58	95
Revolving Loans Converted to Term		2	1
Total loans, net		538	640
Other consumer | 720 to 779 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		151	250
Year two		179	172
Year three		107	167
Year four		102	68
Year five		38	15
Prior		21	19
Revolving Loans		99	125
Revolving Loans Converted to Term		3
Total loans, net		700	816
Other consumer | 660 to 719 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		124	190
Year two		138	145
Year three		98	165
Year four		106	82
Year five		49	16
Prior		15	11
Revolving Loans		99	122
Revolving Loans Converted to Term		2
Total loans, net		631	731
Other consumer | Less than 660 | Using FICO Credit Metric
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		6	50
Year two		51	62
Year three		49	85
Year four		57	54
Year five		33	10
Prior		9	6
Revolving Loans		44	50
Revolving Loans Converted to Term		1	1
Total loans, net		250	318
Other consumer | Other internal credit metrics
Financing Receivable, Credit Quality Indicator [Line Items]
Year one		60	87
Year two		46	31
Year three		35	35
Year four		58	23
Year five		15	22
Prior		44	48
Revolving Loans		3,158	2,955
Revolving Loans Converted to Term		27	21
Total loans, net		$ 3,443	$ 3,222

[1] Our consolidated assets included the following for which we have elected the fair value option: Loans held for sale of $1.0 billion, Loans held for investment of $1.3 billion and Other assets of $0.1 billion at June 30, 2022. Comparable amounts at December 31, 2021 were $1.9 billion, $1.5 billion and $0.1 billion, respectively.