Asset Quality - Schedule of Consumer Credit Exposure (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 109,885	$ 112,606
Accrued interest	508	522
Total consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current	69	1,295
Writeoff, current period	1	0
One year prior	1,293	8,602
Writeoff, one year period	1	12
Two years prior	8,633	12,343
Writeoff, two year period	4	10
Three years prior	11,192	4,151
Writeoff, three year period	3	6
Four years prior	4,292	1,277
Writeoff, four year period	2	5
Prior	3,756	2,131
Writeoff, prior	3	6
Revolving Loans Amortized Cost Basis	4,560	4,747
Writeoff, Revolving Loans Amortized Cost Basis	16	51
Revolving Loans Converted to Term Loans Amortized Cost Basis	439	469
Revolving Loans Converted to Term Loans Amortized Cost Basis, writeoff	0	1
Total	34,234	35,015
Writeoff, total	30	91
Accrued interest	140	139
Total consumer loans | Real estate — residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Current	22	877
Writeoff, current period	1	0
One year prior	864	6,790
Writeoff, one year period	0	0
Two years prior	6,709	8,622
Writeoff, two year period	0	0
Three years prior	8,347	2,663
Writeoff, three year period	0	0
Four years prior	2,624	693
Writeoff, four year period	0	0
Prior	2,137	1,311
Writeoff, prior	0	1
Revolving Loans Amortized Cost Basis	1	2
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	20,704	20,958
Writeoff, total	1	1
Total consumer loans | Real estate — residential mortgage | 750 and above
Financing Receivable, Credit Quality Indicator [Line Items]
Current	13	680
One year prior	708	5,992
Two years prior	5,958	7,785
Three years prior	7,553	2,392
Four years prior	2,380	586
Prior	1,661	923
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	18,273	18,358
Total consumer loans | Real estate — residential mortgage | 660 to 749
Financing Receivable, Credit Quality Indicator [Line Items]
Current	9	180
One year prior	138	739
Two years prior	685	780
Three years prior	736	248
Four years prior	222	90
Prior	313	240
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	2,103	2,277
Total consumer loans | Real estate — residential mortgage | Less than 660
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0	15
One year prior	16	58
Two years prior	65	56
Three years prior	57	22
Four years prior	21	17
Prior	146	130
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	305	298
Total consumer loans | Real estate — residential mortgage | No Score
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0	2
One year prior	2	1
Two years prior	1	1
Three years prior	1	1
Four years prior	1	0
Prior	17	18
Revolving Loans Amortized Cost Basis	1	2
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	23	25
Total consumer loans | Home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current	11	29
Writeoff, current period	0
One year prior	63	163
Writeoff, one year period	0
Two years prior	229	1,842
Writeoff, two year period	0
Three years prior	1,097	614
Writeoff, three year period	0
Four years prior	843	197
Writeoff, four year period	0
Prior	1,127	620
Writeoff, prior	1
Revolving Loans Amortized Cost Basis	3,096	3,205
Writeoff, Revolving Loans Amortized Cost Basis	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	439	469
Revolving Loans Converted to Term Loans Amortized Cost Basis, writeoff	0
Total	6,905	7,139
Writeoff, total	1
Total consumer loans | Home equity loans | 750 and above
Financing Receivable, Credit Quality Indicator [Line Items]
Current	8	0
One year prior	36	85
Two years prior	154	1,575
Three years prior	842	435
Four years prior	673	114
Prior	813	378
Revolving Loans Amortized Cost Basis	1,973	2,034
Revolving Loans Converted to Term Loans Amortized Cost Basis	310	331
Total	4,809	4,952
Total consumer loans | Home equity loans | 660 to 749
Financing Receivable, Credit Quality Indicator [Line Items]
Current	3	24
One year prior	23	65
Two years prior	61	229
Three years prior	216	152
Four years prior	143	66
Prior	219	164
Revolving Loans Amortized Cost Basis	840	886
Revolving Loans Converted to Term Loans Amortized Cost Basis	101	107
Total	1,606	1,693
Total consumer loans | Home equity loans | Less than 660
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0	3
One year prior	4	13
Two years prior	14	38
Three years prior	39	27
Four years prior	27	17
Prior	93	77
Revolving Loans Amortized Cost Basis	279	281
Revolving Loans Converted to Term Loans Amortized Cost Basis	28	31
Total	484	487
Total consumer loans | Home equity loans | No Score
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0	2
One year prior	0	0
Two years prior	0	0
Three years prior	0	0
Four years prior	0	0
Prior	2	1
Revolving Loans Amortized Cost Basis	4	4
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	6	7
Total consumer loans | Home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Writeoff, current period		(1)
Writeoff, one year period		0
Writeoff, two year period		0
Writeoff, three year period		0
Writeoff, four year period		0
Writeoff, prior		2
Writeoff, Revolving Loans Amortized Cost Basis		0
Revolving Loans Converted to Term Loans Amortized Cost Basis, writeoff		1
Writeoff, total		2
Total consumer loans | Other consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current	36	389
Writeoff, current period	0	1
One year prior	366	1,649
Writeoff, one year period	1	12
Two years prior	1,695	1,879
Writeoff, two year period	4	10
Three years prior	1,748	874
Writeoff, three year period	3	6
Four years prior	825	387
Writeoff, four year period	2	5
Prior	492	200
Writeoff, prior	2	3
Revolving Loans Amortized Cost Basis	528	538
Writeoff, Revolving Loans Amortized Cost Basis	4	14
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis, writeoff	0	0
Total	5,690	5,916
Writeoff, total	16	51
Total consumer loans | Other consumer loans | 750 and above
Financing Receivable, Credit Quality Indicator [Line Items]
Current	18	185
One year prior	179	1,187
Two years prior	1,268	1,455
Three years prior	1,345	660
Four years prior	632	277
Prior	306	112
Revolving Loans Amortized Cost Basis	87	97
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	3,835	3,973
Total consumer loans | Other consumer loans | 660 to 749
Financing Receivable, Credit Quality Indicator [Line Items]
Current	11	150
One year prior	137	365
Two years prior	333	342
Three years prior	322	171
Four years prior	154	83
Prior	134	60
Revolving Loans Amortized Cost Basis	189	199
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	1,280	1,370
Total consumer loans | Other consumer loans | Less than 660
Financing Receivable, Credit Quality Indicator [Line Items]
Current	1	24
One year prior	26	64
Two years prior	64	65
Three years prior	64	32
Four years prior	31	17
Prior	32	16
Revolving Loans Amortized Cost Basis	56	57
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	274	275
Total consumer loans | Other consumer loans | No Score
Financing Receivable, Credit Quality Indicator [Line Items]
Current	6	30
One year prior	24	33
Two years prior	30	17
Three years prior	17	11
Four years prior	8	10
Prior	20	12
Revolving Loans Amortized Cost Basis	196	185
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	301	298
Total consumer loans | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Current	0	0
Writeoff, current period	0	0
One year prior	0	0
Writeoff, one year period	0	0
Two years prior	0	0
Writeoff, two year period	0	0
Three years prior	0	0
Writeoff, three year period	0	0
Four years prior	0	0
Writeoff, four year period	0	0
Prior	0	0
Writeoff, prior	0	0
Revolving Loans Amortized Cost Basis	935	1,002
Writeoff, Revolving Loans Amortized Cost Basis	12	37
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis, writeoff	0	0
Total	935	1,002
Writeoff, total	12	37
Total consumer loans | Credit cards | 750 and above
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	442	489
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	442	489
Total consumer loans | Credit cards | 660 to 749
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	381	400
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	381	400
Total consumer loans | Credit cards | Less than 660
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	111	112
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	111	112
Total consumer loans | Credit cards | No Score
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	1	1
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	$ 1	$ 1