Asset Quality Asset Quality - Consumer Credit Exposure (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 106,159	$ 94,646
Accrued interest	225	244
Consumer Loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	5,026
2019	6,727
2018	1,955
2017	1,353
2016	1,405
Prior	4,014
Revolving Loans Amortized Cost Basis	6,805
Revolving Loans Converted to Term Loans Amortized Cost Basis	669
Total	27,954	26,614
Accrued interest	104
Consumer Loans | Real estate — residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,046
2019	2,308
2018	417
2017	406
2016	797
Prior	2,175
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	8,149	7,023
Consumer Loans | Real estate — residential mortgage | FICO Score, 750 and above
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,681
2019	1,878
2018	294
2017	320
2016	648
Prior	1,523
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	6,344
Consumer Loans | Real estate — residential mortgage | FICO Score, 660 to 749
Financing Receivable, Credit Quality Indicator [Line Items]
2020	348
2019	398
2018	96
2017	67
2016	115
Prior	402
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	1,426
Consumer Loans | Real estate — residential mortgage | FICO Score, Less than 660
Financing Receivable, Credit Quality Indicator [Line Items]
2020	17
2019	30
2018	24
2017	12
2016	32
Prior	193
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	308
Consumer Loans | Real estate — residential mortgage | FICO Score, No Score
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	2
2018	3
2017	7
2016	2
Prior	57
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	71
Consumer Loans | Home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	583
2019	781
2018	348
2017	378
2016	349
Prior	1,496
Revolving Loans Amortized Cost Basis	5,178
Revolving Loans Converted to Term Loans Amortized Cost Basis	669
Total	9,782	10,274
Consumer Loans | Home equity loans | FICO Score, 750 and above
Financing Receivable, Credit Quality Indicator [Line Items]
2020	386
2019	450
2018	190
2017	217
2016	206
Prior	901
Revolving Loans Amortized Cost Basis	2,809
Revolving Loans Converted to Term Loans Amortized Cost Basis	406
Total	5,565
Consumer Loans | Home equity loans | FICO Score, 660 to 749
Financing Receivable, Credit Quality Indicator [Line Items]
2020	176
2019	275
2018	125
2017	129
2016	106
Prior	428
Revolving Loans Amortized Cost Basis	1,760
Revolving Loans Converted to Term Loans Amortized Cost Basis	196
Total	3,195
Consumer Loans | Home equity loans | FICO Score, Less than 660
Financing Receivable, Credit Quality Indicator [Line Items]
2020	19
2019	54
2018	32
2017	32
2016	37
Prior	164
Revolving Loans Amortized Cost Basis	604
Revolving Loans Converted to Term Loans Amortized Cost Basis	65
Total	1,007
Consumer Loans | Home equity loans | FICO Score, No Score
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2
2019	2
2018	1
2017	0
2016	0
Prior	3
Revolving Loans Amortized Cost Basis	5
Revolving Loans Converted to Term Loans Amortized Cost Basis	2
Total	15
Consumer Loans | Consumer direct loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,420
2019	1,657
2018	301
2017	104
2016	58
Prior	134
Revolving Loans Amortized Cost Basis	653
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	4,327	3,513
Consumer Loans | Consumer direct loans | FICO Score, 750 and above
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,113
2019	1,214
2018	146
2017	44
2016	24
Prior	69
Revolving Loans Amortized Cost Basis	127
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	2,737
Consumer Loans | Consumer direct loans | FICO Score, 660 to 749
Financing Receivable, Credit Quality Indicator [Line Items]
2020	274
2019	351
2018	101
2017	32
2016	18
Prior	39
Revolving Loans Amortized Cost Basis	270
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	1,085
Consumer Loans | Consumer direct loans | FICO Score, Less than 660
Financing Receivable, Credit Quality Indicator [Line Items]
2020	10
2019	43
2018	28
2017	11
2016	7
Prior	13
Revolving Loans Amortized Cost Basis	98
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	210
Consumer Loans | Consumer direct loans | FICO Score, No Score
Financing Receivable, Credit Quality Indicator [Line Items]
2020	23
2019	49
2018	26
2017	17
2016	9
Prior	13
Revolving Loans Amortized Cost Basis	158
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	295
Consumer Loans | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Loans Amortized Cost Basis	974
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	974	1,130
Consumer Loans | Credit cards | FICO Score, 750 and above
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Loans Amortized Cost Basis	450
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	450
Consumer Loans | Credit cards | FICO Score, 660 to 749
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Loans Amortized Cost Basis	416
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	416
Consumer Loans | Credit cards | FICO Score, Less than 660
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Loans Amortized Cost Basis	107
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	107
Consumer Loans | Credit cards | FICO Score, No Score
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Loans Amortized Cost Basis	1
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	1
Consumer Loans | Consumer indirect loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	977
2019	1,981
2018	889
2017	465
2016	201
Prior	209
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	4,722	$ 4,674
Consumer Loans | Consumer indirect loans | FICO Score, 750 and above
Financing Receivable, Credit Quality Indicator [Line Items]
2020	557
2019	1,056
2018	457
2017	254
2016	107
Prior	97
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	2,528
Consumer Loans | Consumer indirect loans | FICO Score, 660 to 749
Financing Receivable, Credit Quality Indicator [Line Items]
2020	336
2019	717
2018	303
2017	137
2016	57
Prior	73
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	1,623
Consumer Loans | Consumer indirect loans | FICO Score, Less than 660
Financing Receivable, Credit Quality Indicator [Line Items]
2020	69
2019	208
2018	129
2017	74
2016	37
Prior	39
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	556
Consumer Loans | Consumer indirect loans | FICO Score, No Score
Financing Receivable, Credit Quality Indicator [Line Items]
2020	15
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total	$ 15