Asset Quality - Schedule of Commercial Credit Exposure (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 105,346	$ 112,606
Accrued interest	480	522
Total commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current	5,252	6,150
Writeoff, current period		1
One year prior	5,715	16,998
Writeoff, one year period		8
Two years prior	14,259	11,508
Writeoff, two year period		36
Three years prior	8,606	4,178
Writeoff, three year period		19
Four years prior	3,296	4,375
Writeoff, four year period		13
Prior	9,296	7,448
Writeoff, prior		42
Revolving Loans Amortized Cost Basis	25,783	26,721
Writeoff, Revolving Loans Amortized Cost Basis		108
Revolving Loans Converted to Term Loans Amortized Cost Basis	210	213
Revolving Loans Converted to Term Loans Amortized Cost Basis, writeoff		0
Total	72,417	77,591
Writeoff, total		227
Accrued interest	344	383
Total commercial loans | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current	4,313	4,118
Writeoff, current period		1
One year prior	3,573	10,555
Writeoff, one year period		7
Two years prior	8,382	6,618
Writeoff, two year period		35
Three years prior	4,786	2,774
Writeoff, three year period		8
Four years prior	2,159	2,219
Writeoff, four year period		11
Prior	4,547	3,774
Writeoff, prior		21
Revolving Loans Amortized Cost Basis	24,859	25,619
Writeoff, Revolving Loans Amortized Cost Basis		105
Revolving Loans Converted to Term Loans Amortized Cost Basis	155	138
Revolving Loans Converted to Term Loans Amortized Cost Basis, writeoff		0
Total	52,774	55,815
Writeoff, total		188
Total commercial loans | Commercial and Industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current	4,215	4,020
One year prior	3,330	10,145
Two years prior	7,612	6,141
Three years prior	4,309	2,539
Four years prior	1,895	2,064
Prior	4,090	3,534
Revolving Loans Amortized Cost Basis	22,943	24,395
Revolving Loans Converted to Term Loans Amortized Cost Basis	117	123
Total	48,511	52,961
Total commercial loans | Commercial and Industrial | Criticized (Accruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	76	84
One year prior	224	361
Two years prior	664	427
Three years prior	442	233
Four years prior	261	127
Prior	414	170
Revolving Loans Amortized Cost Basis	1,779	1,140
Revolving Loans Converted to Term Loans Amortized Cost Basis	38	15
Total	3,898	2,557
Total commercial loans | Commercial and Industrial | Criticized (Nonaccruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	22	14
One year prior	19	49
Two years prior	106	50
Three years prior	35	2
Four years prior	3	28
Prior	43	70
Revolving Loans Amortized Cost Basis	137	84
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	365	297
Total commercial loans | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Writeoff, current period	0
Writeoff, one year period	6
Writeoff, two year period	40
Writeoff, three year period	105
Writeoff, four year period	4
Writeoff, prior	25
Writeoff, Revolving Loans Amortized Cost Basis	99
Revolving Loans Converted to Term Loans Amortized Cost Basis, writeoff	0
Writeoff, total	279
Total commercial loans | Real estate — commercial mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Current	642	1,090
Writeoff, current period	0	0
One year prior	874	4,310
Writeoff, one year period	0	1
Two years prior	3,887	3,334
Writeoff, two year period	0	1
Three years prior	2,787	822
Writeoff, three year period	0	11
Four years prior	718	1,738
Writeoff, four year period	0	2
Prior	3,787	2,755
Writeoff, prior	21	21
Revolving Loans Amortized Cost Basis	889	1,071
Writeoff, Revolving Loans Amortized Cost Basis	1	3
Revolving Loans Converted to Term Loans Amortized Cost Basis	53	67
Revolving Loans Converted to Term Loans Amortized Cost Basis, writeoff	0	0
Total	13,637	15,187
Writeoff, total	22	39
Total commercial loans | Real estate — commercial mortgage | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current	623	1,084
One year prior	808	3,664
Two years prior	3,127	2,922
Three years prior	2,344	804
Four years prior	629	1,545
Prior	3,338	2,507
Revolving Loans Amortized Cost Basis	865	1,017
Revolving Loans Converted to Term Loans Amortized Cost Basis	42	66
Total	11,776	13,609
Total commercial loans | Real estate — commercial mortgage | Criticized (Accruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	19	6
One year prior	66	646
Two years prior	705	411
Three years prior	372	15
Four years prior	87	186
Prior	406	193
Revolving Loans Amortized Cost Basis	22	20
Revolving Loans Converted to Term Loans Amortized Cost Basis	11	1
Total	1,688	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	55	1
Three years prior	71	3
Four years prior	2	7
Prior	43	55
Revolving Loans Amortized Cost Basis	2	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	60	411
Writeoff, current period	0	0
One year prior	773	1,225
Writeoff, one year period	0	0
Two years prior	1,288	972
Writeoff, two year period	0	0
Three years prior	608	221
Writeoff, three year period	0	0
Four years prior	156	103
Writeoff, four year period	0	0
Prior	171	95
Writeoff, prior	0	0
Revolving Loans Amortized Cost Basis	35	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	3,093	3,066
Writeoff, total	0	0
Total commercial loans | Real estate — construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current	60	401
One year prior	757	1,185
Two years prior	1,172	912
Three years prior	466	157
Four years prior	88	62
Prior	93	48
Revolving Loans Amortized Cost Basis	35	31
Revolving Loans Converted to Term Loans Amortized Cost Basis	2	8
Total	2,673	2,804
Total commercial loans | Real estate — construction | Criticized (Accruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0	10
One year prior	16	40
Two years prior	116	60
Three years prior	142	64
Four years prior	68	41
Prior	78	47
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	420	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	237	531
Writeoff, current period	0	0
One year prior	495	908
Writeoff, one year period	0	0
Two years prior	702	584
Writeoff, two year period	0	0
Three years prior	425	361
Writeoff, three year period	0	0
Four years prior	263	315
Writeoff, four year period	0	0
Prior	791	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	2,913	3,523
Writeoff, total	6	0
Total commercial loans | Commercial lease financing | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current	235	520
One year prior	465	878
Two years prior	685	575
Three years prior	415	352
Four years prior	255	307
Prior	777	808
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	2,832	3,440
Total commercial loans | Commercial lease financing | Criticized (Accruing)
Financing Receivable, Credit Quality Indicator [Line Items]
Current	2	11
One year prior	30	30
Two years prior	17	9
Three years prior	10	9
Four years prior	8	8
Prior	14	16
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	81	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	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
Financing Receivable, Credit Quality Indicator [Line Items]
Writeoff, current period	0
Writeoff, one year period	6
Writeoff, two year period	40
Writeoff, three year period	105
Writeoff, four year period	4
Writeoff, prior	52
Writeoff, Revolving Loans Amortized Cost Basis	100
Revolving Loans Converted to Term Loans Amortized Cost Basis, writeoff	0
Writeoff, total	$ 307