Asset Quality - Consumer 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
Consumer Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current	13,637
One year prior	5,890
Two years prior	2,095
Three years prior	432
Four years prior	384
Prior	2,812
Revolving Loans Amortized Cost Basis	5,156
Revolving Loans Converted to Term Loans Amortized Cost Basis	612
Total loans	31,018	29,205
Accrued interest	85
Consumer Loans | Real estate — residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Current	9,636
One year prior	3,274
Two years prior	966
Three years prior	140
Four years prior	163
Prior	1,576
Revolving Loans Amortized Cost Basis	1
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	15,756	9,298
Consumer Loans | Real estate — residential mortgage | FICO Score, 750 and above
Financing Receivable, Credit Quality Indicator [Line Items]
Current	7,906
One year prior	2,909
Two years prior	777
Three years prior	84
Four years prior	126
Prior	1,096
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	12,898
Consumer Loans | Real estate — residential mortgage | FICO Score, 660 to 749
Financing Receivable, Credit Quality Indicator [Line Items]
Current	1,686
One year prior	351
Two years prior	169
Three years prior	39
Four years prior	25
Prior	308
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	2,578
Consumer Loans | Real estate — residential mortgage | FICO Score, Less than 660
Financing Receivable, Credit Quality Indicator [Line Items]
Current	26
One year prior	14
Two years prior	19
Three years prior	16
Four years prior	9
Prior	142
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	226
Consumer Loans | Real estate — residential mortgage | FICO Score, No Score
Financing Receivable, Credit Quality Indicator [Line Items]
Current	18
One year prior	0
Two years prior	1
Three years prior	1
Four years prior	3
Prior	30
Revolving Loans Amortized Cost Basis	1
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	54
Consumer Loans | Home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current	1,472
One year prior	1,119
Two years prior	382
Three years prior	153
Four years prior	181
Prior	964
Revolving Loans Amortized Cost Basis	3,584
Revolving Loans Converted to Term Loans Amortized Cost Basis	612
Total loans	8,467	9,360
Consumer Loans | Home equity loans | FICO Score, 750 and above
Financing Receivable, Credit Quality Indicator [Line Items]
Current	1,051
One year prior	830
Two years prior	251
Three years prior	96
Four years prior	128
Prior	666
Revolving Loans Amortized Cost Basis	2,244
Revolving Loans Converted to Term Loans Amortized Cost Basis	423
Total loans	5,689
Consumer Loans | Home equity loans | FICO Score, 660 to 749
Financing Receivable, Credit Quality Indicator [Line Items]
Current	394
One year prior	263
Two years prior	111
Three years prior	44
Four years prior	40
Prior	204
Revolving Loans Amortized Cost Basis	1,004
Revolving Loans Converted to Term Loans Amortized Cost Basis	143
Total loans	2,203
Consumer Loans | Home equity loans | FICO Score, Less than 660
Financing Receivable, Credit Quality Indicator [Line Items]
Current	27
One year prior	24
Two years prior	20
Three years prior	13
Four years prior	13
Prior	92
Revolving Loans Amortized Cost Basis	333
Revolving Loans Converted to Term Loans Amortized Cost Basis	46
Total loans	568
Consumer Loans | Home equity loans | FICO Score, No Score
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0
One year prior	2
Two years prior	0
Three years prior	0
Four years prior	0
Prior	2
Revolving Loans Amortized Cost Basis	3
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	7
Consumer Loans | Consumer direct loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current	2,524
One year prior	1,497
Two years prior	747
Three years prior	139
Four years prior	40
Prior	207
Revolving Loans Amortized Cost Basis	599
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	5,753	4,714
Consumer Loans | Consumer direct loans | FICO Score, 750 and above
Financing Receivable, Credit Quality Indicator [Line Items]
Current	1,799
One year prior	1,129
Two years prior	517
Three years prior	65
Four years prior	17
Prior	129
Revolving Loans Amortized Cost Basis	109
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	3,765
Consumer Loans | Consumer direct loans | FICO Score, 660 to 749
Financing Receivable, Credit Quality Indicator [Line Items]
Current	612
One year prior	295
Two years prior	174
Three years prior	46
Four years prior	10
Prior	45
Revolving Loans Amortized Cost Basis	212
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	1,394
Consumer Loans | Consumer direct loans | FICO Score, Less than 660
Financing Receivable, Credit Quality Indicator [Line Items]
Current	45
One year prior	33
Two years prior	27
Three years prior	11
Four years prior	3
Prior	12
Revolving Loans Amortized Cost Basis	60
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	191
Consumer Loans | Consumer direct loans | FICO Score, No Score
Financing Receivable, Credit Quality Indicator [Line Items]
Current	68
One year prior	40
Two years prior	29
Three years prior	17
Four years prior	10
Prior	21
Revolving Loans Amortized Cost Basis	218
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	403
Consumer Loans | Commercial credit card
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0
One year prior	0
Two years prior	0
Three years prior	0
Four years prior	0
Prior	0
Revolving Loans Amortized Cost Basis	972
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	972	989
Consumer Loans | Commercial credit card | FICO Score, 750 and above
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0
One year prior	0
Two years prior	0
Three years prior	0
Four years prior	0
Prior	0
Revolving Loans Amortized Cost Basis	500
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	500
Consumer Loans | Commercial credit card | FICO Score, 660 to 749
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0
One year prior	0
Two years prior	0
Three years prior	0
Four years prior	0
Prior	0
Revolving Loans Amortized Cost Basis	387
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	387
Consumer Loans | Commercial credit card | FICO Score, Less than 660
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0
One year prior	0
Two years prior	0
Three years prior	0
Four years prior	0
Prior	0
Revolving Loans Amortized Cost Basis	84
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	84
Consumer Loans | Commercial credit card | FICO Score, No Score
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0
One year prior	0
Two years prior	0
Three years prior	0
Four years prior	0
Prior	0
Revolving Loans Amortized Cost Basis	1
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	1
Consumer Loans | Consumer indirect loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current	5
One year prior	0
Two years prior	0
Three years prior	0
Four years prior	0
Prior	65
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	70	$ 4,844
Consumer Loans | Consumer indirect loans | FICO Score, 750 and above
Financing Receivable, Credit Quality Indicator [Line Items]
Current	5
One year prior	0
Two years prior	0
Three years prior	0
Four years prior	0
Prior	30
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	35
Consumer Loans | Consumer indirect loans | FICO Score, 660 to 749
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0
One year prior	0
Two years prior	0
Three years prior	0
Four years prior	0
Prior	26
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	26
Consumer Loans | Consumer indirect loans | FICO Score, Less than 660
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0
One year prior	0
Two years prior	0
Three years prior	0
Four years prior	0
Prior	9
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	9
Consumer Loans | Consumer indirect loans | FICO Score, No Score
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0
One year prior	0
Two years prior	0
Three years prior	0
Four years prior	0
Prior	0
Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0
Total loans	$ 0