Loans and Allowance for Loan Losses - Loans in Consumer Portfolio Segment Based FICO Scores, Non-Revolving And Revolving Loans (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	$ 86,535	$ 88,213
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,153
2019	7,629
2018	4,499
2017	7,232
2016	6,494
Prior	8,185
Revolving Loans	1,457
Financing receivable	$ 37,649	$ 42,468
2020 Percentage	6.00%
2019 Percentage	20.00%
2018 Percentage	12.00%
2017 Percentage	19.00%
2016 Percentage	17.00%
Prior Percentage	22.00%
Revolving Percentage	4.00%
Total	100.00%
Consumer | Residential mortgage and home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 1,629
2019	5,372
2018	3,796
2017	7,178
2016	6,485
Prior	8,150
Revolving Loans	1,184
Financing receivable	$ 33,794
2020 Percentage	5.00%
2019 Percentage	16.00%
2018 Percentage	11.00%
2017 Percentage	21.00%
2016 Percentage	19.00%
Prior Percentage	24.00%
Revolving Percentage	4.00%
Total	100.00%
Consumer | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 524
2019	2,257
2018	703
2017	54
2016	9
Prior	35
Revolving Loans	273
Financing receivable	3,855
FICO Score 720 and Above | Consumer | Residential mortgage and home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,407
2019	4,628
2018	3,157
2017	6,037
2016	5,613
Prior	6,352
Revolving Loans	931
Financing receivable	28,125
FICO Score 720 and Above | Consumer | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	347
2019	1,329
2018	423
2017	33
2016	5
Prior	6
Revolving Loans	118
Financing receivable	2,261
FICO Score Below 720 | Consumer | Residential mortgage and home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2020	205
2019	726
2018	626
2017	1,088
2016	831
Prior	1,511
Revolving Loans	240
Financing receivable	5,227
FICO Score Below 720 | Consumer | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	177
2019	928
2018	280
2017	21
2016	4
Prior	4
Revolving Loans	153
Financing receivable	1,567
No FICO Available | Consumer | Residential mortgage and home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2020	17
2019	18
2018	13
2017	53
2016	41
Prior	287
Revolving Loans	13
Financing receivable	442
No FICO Available | Consumer | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	25
Revolving Loans	2
Financing receivable	$ 27