Loans and Allowance for Loan Losses - Loans in Consumer Portfolio Segment Based On LTV Ratios, Revolving and Nonrevolving (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Credit quality of consumer loans
Financing receivable	$ 84,974	$ 88,213
Consumer
Credit quality of consumer loans
2020	3,549
2019	6,807
2018	3,810
2017	6,345
2016	5,770
Prior	7,342
Revolving Loans	1,370
Financing receivable	$ 34,993	$ 42,468
2020 Percentage	10.00%
2019 Percentage	20.00%
2018 Percentage	11.00%
2017 Percentage	18.00%
2016 Percentage	16.00%
Prior Percentage	21.00%
Revolving Percentage	4.00%
Total	100.00%
Consumer | Residential mortgage and home equity
Credit quality of consumer loans
2020	$ 3,007
2019	4,862
2018	3,256
2017	6,306
2016	5,764
Prior	7,311
Revolving Loans	1,113
Financing receivable	$ 31,619
2020 Percentage	10.00%
2019 Percentage	15.00%
2018 Percentage	10.00%
2017 Percentage	20.00%
2016 Percentage	18.00%
Prior Percentage	23.00%
Revolving Percentage	4.00%
Total	100.00%
Consumer | Residential mortgage and home equity | 80% or below
Credit quality of consumer loans
2020	$ 2,884
2019	4,560
2018	3,064
2017	6,254
2016	5,757
Prior	7,246
Revolving Loans	1,007
Financing receivable	30,772
Consumer | Residential mortgage and home equity | 80% to 100%
Credit quality of consumer loans
2020	121
2019	299
2018	188
2017	49
2016	6
Prior	34
Revolving Loans	101
Financing receivable	798
Consumer | Residential mortgage and home equity | 100% or more
Credit quality of consumer loans
2020	0
2019	0
2018	2
2017	0
2016	0
Prior	3
Revolving Loans	1
Financing receivable	6
Consumer | Residential mortgage and home equity | No LTV Available
Credit quality of consumer loans
2020	2
2019	3
2018	2
2017	3
2016	1
Prior	28
Revolving Loans	4
Financing receivable	43
Consumer Portfolio Segment Related to LTV Ratios
Credit quality of consumer loans
2020	3,007
2019	4,862
2018	3,256
2017	6,306
2016	5,764
Prior	7,311
Revolving Loans	1,113
Financing receivable	$ 31,619