Asset Quality - Schedule of Commercial Credit Exposure (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2024	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 107,078	$ 112,606
Accrued interest	502	522
Total commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current	3,119	6,150
Writeoff, current period		1
One year prior	5,794	16,998
Writeoff, one year period		8
Two years prior	15,074	11,508
Writeoff, two year period		36
Three years prior	9,748	4,178
Writeoff, three year period		19
Four years prior	3,549	4,375
Writeoff, four year period		13
Prior	10,534	7,448
Writeoff, prior		42
Revolving Loans Amortized Cost Basis	25,484	26,721
Writeoff, Revolving Loans Amortized Cost Basis		108
Revolving Loans Converted to Term Loans Amortized Cost Basis	223	213
Revolving Loans Converted to Term Loans Amortized Cost Basis, writeoff		0
Total	73,525	77,591
Writeoff, total		227
Accrued interest	365	383
Total commercial loans | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current	2,551	4,118
Writeoff, current period		1
One year prior	3,715	10,555
Writeoff, one year period		7
Two years prior	8,970	6,618
Writeoff, two year period		35
Three years prior	5,471	2,774
Writeoff, three year period		8
Four years prior	2,355	2,219
Writeoff, four year period		11
Prior	5,419	3,774
Writeoff, prior		21
Revolving Loans Amortized Cost Basis	24,482	25,619
Writeoff, Revolving Loans Amortized Cost Basis		105
Revolving Loans Converted to Term Loans Amortized Cost Basis	166	138
Revolving Loans Converted to Term Loans Amortized Cost Basis, writeoff		0
Total	53,129	55,815
Writeoff, total		188
Total commercial loans | Commercial and Industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current	2,469	4,020
One year prior	3,479	10,145
Two years prior	8,119	6,141
Three years prior	4,902	2,539
Four years prior	2,104	2,064
Prior	4,912	3,534
Revolving Loans Amortized Cost Basis	22,751	24,395
Revolving Loans Converted to Term Loans Amortized Cost Basis	119	123
Total	48,855	52,961
Total commercial loans | Commercial and Industrial | Criticized (Accruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	64	84
One year prior	218	361
Two years prior	782	427
Three years prior	498	233
Four years prior	248	127
Prior	450	170
Revolving Loans Amortized Cost Basis	1,609	1,140
Revolving Loans Converted to Term Loans Amortized Cost Basis	47	15
Total	3,916	2,557
Total commercial loans | Commercial and Industrial | Criticized (Nonaccruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	18	14
One year prior	18	49
Two years prior	69	50
Three years prior	71	2
Four years prior	3	28
Prior	57	70
Revolving Loans Amortized Cost Basis	122	84
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	358	297
Total commercial loans | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Writeoff, current period	(2)
Writeoff, one year period	4
Writeoff, two year period	29
Writeoff, three year period	46
Writeoff, four year period	3
Writeoff, prior	17
Writeoff, Revolving Loans Amortized Cost Basis	51
Revolving Loans Converted to Term Loans Amortized Cost Basis, writeoff	0
Writeoff, total	148
Total commercial loans | Real estate — commercial mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Current	408	1,090
Writeoff, current period	0	0
One year prior	858	4,310
Writeoff, one year period	0	1
Two years prior	4,106	3,334
Writeoff, two year period	0	1
Three years prior	3,032	822
Writeoff, three year period	0	11
Four years prior	753	1,738
Writeoff, four year period	0	2
Prior	4,032	2,755
Writeoff, prior	14	21
Revolving Loans Amortized Cost Basis	974	1,071
Writeoff, Revolving Loans Amortized Cost Basis	1	3
Revolving Loans Converted to Term Loans Amortized Cost Basis	55	67
Revolving Loans Converted to Term Loans Amortized Cost Basis, writeoff	0	0
Total	14,218	15,187
Writeoff, total	15	39
Total commercial loans | Real estate — commercial mortgage | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current	405	1,084
One year prior	790	3,664
Two years prior	3,329	2,922
Three years prior	2,525	804
Four years prior	687	1,545
Prior	3,525	2,507
Revolving Loans Amortized Cost Basis	924	1,017
Revolving Loans Converted to Term Loans Amortized Cost Basis	51	66
Total	12,236	13,609
Total commercial loans | Real estate — commercial mortgage | Criticized (Accruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	3	6
One year prior	68	646
Two years prior	754	411
Three years prior	437	15
Four years prior	63	186
Prior	460	193
Revolving Loans Amortized Cost Basis	20	20
Revolving Loans Converted to Term Loans Amortized Cost Basis	4	1
Total	1,809	1,478
Total commercial loans | Real estate — commercial mortgage | Criticized (Nonaccruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0	0
One year prior	0	0
Two years prior	23	1
Three years prior	70	3
Four years prior	3	7
Prior	47	55
Revolving Loans Amortized Cost Basis	30	34
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	173	100
Total commercial loans | Real estate — construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current	21	411
Writeoff, current period	0	0
One year prior	674	1,225
Writeoff, one year period	0	0
Two years prior	1,249	972
Writeoff, two year period	0	0
Three years prior	785	221
Writeoff, three year period	0	0
Four years prior	142	103
Writeoff, four year period	0	0
Prior	176	95
Writeoff, prior	0	0
Revolving Loans Amortized Cost Basis	28	31
Writeoff, Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	2	8
Revolving Loans Converted to Term Loans Amortized Cost Basis, writeoff	0	0
Total	3,077	3,066
Writeoff, total	0	0
Total commercial loans | Real estate — construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current	21	401
One year prior	659	1,185
Two years prior	1,157	912
Three years prior	624	157
Four years prior	69	62
Prior	108	48
Revolving Loans Amortized Cost Basis	28	31
Revolving Loans Converted to Term Loans Amortized Cost Basis	2	8
Total	2,668	2,804
Total commercial loans | Real estate — construction | Criticized (Accruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0	10
One year prior	15	40
Two years prior	92	60
Three years prior	161	64
Four years prior	73	41
Prior	68	47
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	409	262
Total commercial loans | Real estate — 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
Total commercial loans | Commercial lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Current	139	531
Writeoff, current period	0	0
One year prior	547	908
Writeoff, one year period	0	0
Two years prior	749	584
Writeoff, two year period	0	0
Three years prior	460	361
Writeoff, three year period	0	0
Four years prior	299	315
Writeoff, four year period	0	0
Prior	907	824
Writeoff, prior	6	0
Revolving Loans Amortized Cost Basis		0
Writeoff, Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis, writeoff	0	0
Total	3,101	3,523
Writeoff, total	6	0
Total commercial loans | Commercial lease financing | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current	139	520
One year prior	517	878
Two years prior	712	575
Three years prior	455	352
Four years prior	290	307
Prior	890	808
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	3,003	3,440
Total commercial loans | Commercial lease financing | Criticized (Accruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0	11
One year prior	30	30
Two years prior	37	9
Three years prior	5	9
Four years prior	9	8
Prior	16	16
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	97	83
Total 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	0
Three years prior	0	0
Four years prior	0	0
Prior	1	0
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	1	$ 0
Total commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Writeoff, current period	(2)
Writeoff, one year period	4
Writeoff, two year period	29
Writeoff, three year period	46
Writeoff, four year period	3
Writeoff, prior	37
Writeoff, Revolving Loans Amortized Cost Basis	52
Revolving Loans Converted to Term Loans Amortized Cost Basis, writeoff	0
Writeoff, total	$ 169