Asset Quality - Commercial Credit Exposure (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	$ 101,854	$ 101,185
Commercial Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current	18,212
One year prior	7,556
Two years prior	7,624
Three years prior	4,772
Four years prior	3,136
Prior	7,235
Revolving Loans Amortized Cost Basis	22,159
Revolving Loans Converted to Term Loans Amortized Cost Basis	142
Total loans	70,836	71,980
Accrued interest	113
Commercial Loans | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current	11,740
One year prior	5,013
Two years prior	4,176
Three years prior	2,956
Four years prior	1,996
Prior	3,244
Revolving Loans Amortized Cost Basis	21,312
Revolving Loans Converted to Term Loans Amortized Cost Basis	88
Total loans	50,525	52,907
Accrued interest	198	241
Commercial Loans | Commercial and industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current	11,675
One year prior	4,941
Two years prior	4,040
Three years prior	2,771
Four years prior	1,777
Prior	3,108
Revolving Loans Amortized Cost Basis	20,406
Revolving Loans Converted to Term Loans Amortized Cost Basis	72
Total loans	48,790
Commercial Loans | Commercial and industrial | Criticized (Accruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	64
One year prior	71
Two years prior	115
Three years prior	175
Four years prior	200
Prior	121
Revolving Loans Amortized Cost Basis	784
Revolving Loans Converted to Term Loans Amortized Cost Basis	14
Total loans	1,544
Commercial Loans | Commercial and industrial | Criticized (Nonaccruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	1
One year prior	1
Two years prior	21
Three years prior	10
Four years prior	19
Prior	15
Revolving Loans Amortized Cost Basis	122
Revolving Loans Converted to Term Loans Amortized Cost Basis	2
Total loans	191
Commercial Loans | Commercial mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Current	4,938
One year prior	1,220
Two years prior	2,208
Three years prior	1,235
Four years prior	721
Prior	3,024
Revolving Loans Amortized Cost Basis	844
Revolving Loans Converted to Term Loans Amortized Cost Basis	54
Total loans	14,244	12,687
Commercial Loans | Commercial mortgage | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current	4,923
One year prior	1,197
Two years prior	2,137
Three years prior	1,168
Four years prior	612
Prior	2,787
Revolving Loans Amortized Cost Basis	803
Revolving Loans Converted to Term Loans Amortized Cost Basis	53
Total loans	13,680
Commercial Loans | Commercial mortgage | Criticized (Accruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	15
One year prior	22
Two years prior	70
Three years prior	62
Four years prior	109
Prior	206
Revolving Loans Amortized Cost Basis	35
Revolving Loans Converted to Term Loans Amortized Cost Basis	1
Total loans	520
Commercial Loans | Commercial mortgage | Criticized (Nonaccruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0
One year prior	1
Two years prior	1
Three years prior	5
Four years prior	0
Prior	31
Revolving Loans Amortized Cost Basis	6
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	44
Commercial Loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current	495
One year prior	569
Two years prior	535
Three years prior	266
Four years prior	96
Prior	32
Revolving Loans Amortized Cost Basis	3
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	1,996	1,987
Commercial Loans | Construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current	495
One year prior	565
Two years prior	530
Three years prior	223
Four years prior	92
Prior	32
Revolving Loans Amortized Cost Basis	2
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	1,939
Commercial Loans | Construction | Criticized (Accruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0
One year prior	4
Two years prior	5
Three years prior	43
Four years prior	4
Prior	0
Revolving Loans Amortized Cost Basis	1
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	57
Commercial Loans | Construction | Criticized (Nonaccruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0
One year prior	0
Two years prior	0
Three years prior	0
Prior	0
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	0
Commercial Loans | Commercial lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Current	1,039
One year prior	754
Two years prior	705
Three years prior	315
Four years prior	323
Prior	935
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	4,071	$ 4,399
Commercial Loans | Commercial lease financing | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current	1,039
One year prior	748
Two years prior	675
Three years prior	301
Four years prior	309
Prior	927
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	3,999
Commercial Loans | Commercial lease financing | Criticized (Accruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0
One year prior	6
Two years prior	29
Three years prior	13
Four years prior	13
Prior	7
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	68
Commercial Loans | Commercial lease financing | Criticized (Nonaccruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0
One year prior	0
Two years prior	1
Three years prior	1
Four years prior	1
Prior	1
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	$ 4