Asset Quality - Commercial Credit Exposure (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 106,600	$ 101,854
Accrued interest	193	198
Commercial Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current	3,729	18,212
One year prior	17,803	7,556
Two years prior	6,970	7,624
Three years prior	6,887	4,772
Four years prior	4,285	3,136
Prior	9,603	7,235
Revolving Loans Amortized Cost Basis	24,439	22,159
Revolving Loans Converted to Term Loans Amortized Cost Basis	204	142
Total	73,920	70,836
Accrued interest	117	113
Commercial Loans | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current	1,952	11,740
One year prior	11,523	5,013
Two years prior	4,486	4,176
Three years prior	3,628	2,956
Four years prior	2,697	1,996
Prior	4,836	3,244
Revolving Loans Amortized Cost Basis	23,552	21,312
Revolving Loans Converted to Term Loans Amortized Cost Basis	141	88
Total	52,815	50,525
Commercial Loans | Commercial and Industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current	1,952	11,675
One year prior	11,488	4,941
Two years prior	4,372	4,040
Three years prior	3,497	2,771
Four years prior	2,515	1,777
Prior	4,511	3,108
Revolving Loans Amortized Cost Basis	22,623	20,406
Revolving Loans Converted to Term Loans Amortized Cost Basis	117	72
Total	51,075	48,790
Commercial Loans | Commercial and Industrial | Criticized (Accruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0	64
One year prior	34	71
Two years prior	111	115
Three years prior	116	175
Four years prior	173	200
Prior	294	121
Revolving Loans Amortized Cost Basis	803	784
Revolving Loans Converted to Term Loans Amortized Cost Basis	23	14
Total	1,554	1,544
Commercial Loans | Commercial and Industrial | Criticized (Nonaccruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0	1
One year prior	1	1
Two years prior	3	21
Three years prior	15	10
Four years prior	9	19
Prior	31	15
Revolving Loans Amortized Cost Basis	126	122
Revolving Loans Converted to Term Loans Amortized Cost Basis	1	2
Total	186	191
Commercial Loans | Commercial mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Current	1,474	4,938
One year prior	4,823	1,220
Two years prior	1,174	2,208
Three years prior	2,133	1,235
Four years prior	1,070	721
Prior	3,504	3,024
Revolving Loans Amortized Cost Basis	886	844
Revolving Loans Converted to Term Loans Amortized Cost Basis	60	54
Total	15,124	14,244
Commercial Loans | Commercial mortgage | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current	1,474	4,923
One year prior	4,805	1,197
Two years prior	1,153	2,137
Three years prior	2,045	1,168
Four years prior	994	612
Prior	3,185	2,787
Revolving Loans Amortized Cost Basis	850	803
Revolving Loans Converted to Term Loans Amortized Cost Basis	59	53
Total	14,565	13,680
Commercial Loans | Commercial mortgage | Criticized (Accruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0	15
One year prior	18	22
Two years prior	20	70
Three years prior	87	62
Four years prior	71	109
Prior	290	206
Revolving Loans Amortized Cost Basis	33	35
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	1
Total	519	520
Commercial Loans | Commercial mortgage | Criticized (Nonaccruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0	0
One year prior	0	1
Two years prior	1	1
Three years prior	1	5
Four years prior	5	0
Prior	29	31
Revolving Loans Amortized Cost Basis	3	6
Revolving Loans Converted to Term Loans Amortized Cost Basis	1	0
Total	40	44
Commercial Loans | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current	144	495
One year prior	472	569
Two years prior	606	535
Three years prior	483	266
Four years prior	240	96
Prior	116	32
Revolving Loans Amortized Cost Basis	1	3
Revolving Loans Converted to Term Loans Amortized Cost Basis	3	0
Total	2,065	1,996
Commercial Loans | Construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current	144	495
One year prior	472	565
Two years prior	602	530
Three years prior	476	223
Four years prior	209	92
Prior	112	32
Revolving Loans Amortized Cost Basis	1	2
Revolving Loans Converted to Term Loans Amortized Cost Basis	3	0
Total	2,019	1,939
Commercial Loans | Construction | Criticized (Accruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0	0
One year prior	0	4
Two years prior	4	5
Three years prior	7	43
Four years prior	31	4
Prior	4	0
Revolving Loans Amortized Cost Basis	0	1
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	46	57
Commercial Loans | Construction | Criticized (Nonaccruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0	0
One year prior	0	0
Two years prior	0	0
Three years prior	0	0
Four years prior	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	0	0
Commercial Loans | Commercial lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Current	159	1,039
One year prior	985	754
Two years prior	704	705
Three years prior	643	315
Four years prior	278	323
Prior	1,147	935
Revolving Loans Amortized Cost Basis		0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	3,916	4,071
Commercial Loans | Commercial lease financing | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current	159	1,039
One year prior	985	748
Two years prior	693	675
Three years prior	619	301
Four years prior	262	309
Prior	1,131	927
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	3,849	3,999
Commercial Loans | Commercial lease financing | Criticized (Accruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0	0
One year prior	0	6
Two years prior	11	29
Three years prior	23	13
Four years prior	15	13
Prior	15	7
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	64	68
Commercial Loans | Commercial lease financing | Criticized (Nonaccruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0	0
One year prior	0	0
Two years prior	0	1
Three years prior	1	1
Four years prior	1	1
Prior	1	1
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	$ 3	$ 4