Loans and Allowance for Credit Losses - Amortized Cost Basis (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	$ 6,637	$ 5,572
Fiscal year before current fiscal year	2,788	3,020
Two years before current fiscal year	2,406	4,685
Three years before current fiscal year	3,970	424
Four years before current fiscal year	333	1,229
Prior	2,040	1,291
Revolving Loans	21,194	20,410
Total	39,368	36,631
Accrued interest receivable	297	318
Loans classified as held-for-sale	8
Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Total	34,850	32,024
Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Total	3,884	3,995
Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total	277	304
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total	164	238
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total	193	70
Commercial and Financial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	36,510	33,562
Commercial and Financial | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Total	32,734	29,737
Commercial and Financial | Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Total	3,529	3,546
Commercial and Financial | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total	215	242
Commercial and Financial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total	32	14
Commercial and Financial | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total	0	23
Commercial and Financial | Domestic
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	2,953	2,019
Fiscal year before current fiscal year	462	409
Two years before current fiscal year	231	1,128
Three years before current fiscal year	727	157
Four years before current fiscal year	57	579
Prior	476	146
Revolving Loans	15,608	15,557
Total	20,514	19,995
Commercial and Financial | Domestic | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,731	1,399
Fiscal year before current fiscal year	223	120
Two years before current fiscal year	100	199
Three years before current fiscal year	163	8
Four years before current fiscal year	6	272
Prior	234	5
Revolving Loans	15,529	15,476
Total	17,986	17,479
Commercial and Financial | Domestic | Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,199	615
Fiscal year before current fiscal year	214	285
Two years before current fiscal year	131	747
Three years before current fiscal year	473	149
Four years before current fiscal year	51	291
Prior	242	141
Revolving Loans	79	81
Total	2,389	2,309
Commercial and Financial | Domestic | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	20	0
Fiscal year before current fiscal year	25	4
Two years before current fiscal year	0	164
Three years before current fiscal year	76	0
Four years before current fiscal year	0	16
Prior	0	0
Revolving Loans	0	0
Total	121	184
Commercial and Financial | Domestic | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	3	5
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	18
Three years before current fiscal year	15	0
Four years before current fiscal year	0	0
Prior	0	0
Revolving Loans	0	0
Total	18	23
Commercial and Financial | Domestic | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0
Fiscal year before current fiscal year	0
Two years before current fiscal year	0
Three years before current fiscal year	0
Four years before current fiscal year	0
Prior	0
Revolving Loans	0
Total	0
Commercial and Financial | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	3,643	3,337
Fiscal year before current fiscal year	2,110	2,091
Two years before current fiscal year	1,655	3,028
Three years before current fiscal year	2,896	117
Four years before current fiscal year	48	109
Prior	59	32
Revolving Loans	5,586	4,853
Total	15,997	13,567
Commercial and Financial | Non-U.S. | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	3,243	2,943
Fiscal year before current fiscal year	1,907	1,956
Two years before current fiscal year	1,572	2,518
Three years before current fiscal year	2,493	0
Four years before current fiscal year	0	0
Prior	0	0
Revolving Loans	5,534	4,841
Total	14,749	12,258
Commercial and Financial | Non-U.S. | Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	400	394
Fiscal year before current fiscal year	203	135
Two years before current fiscal year	83	481
Three years before current fiscal year	309	88
Four years before current fiscal year	48	109
Prior	45	18
Revolving Loans	52	12
Total	1,140	1,237
Commercial and Financial | Non-U.S. | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	29
Three years before current fiscal year	94	29
Four years before current fiscal year	0	0
Prior	0	0
Revolving Loans	0	0
Total	94	58
Commercial and Financial | Non-U.S. | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Prior	14	14
Revolving Loans	0	0
Total	14	14
Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,858	3,069
Commercial real estate | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,116	2,287
Commercial real estate | Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Total	355	449
Commercial real estate | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total	62	62
Commercial real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total	132	224
Commercial real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total	193	47
Commercial real estate | Domestic
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	41	216
Fiscal year before current fiscal year	216	520
Two years before current fiscal year	520	529
Three years before current fiscal year	347	150
Four years before current fiscal year	228	541
Prior	1,505	1,113
Revolving Loans	0	0
Total	2,857	3,069
Commercial real estate | Domestic | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	41	216
Fiscal year before current fiscal year	196	500
Two years before current fiscal year	500	498
Three years before current fiscal year	278	100
Four years before current fiscal year	128	375
Prior	972	598
Revolving Loans	0	0
Total	2,115	2,287
Commercial real estate | Domestic | Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	20	20
Two years before current fiscal year	20	31
Three years before current fiscal year	69	50
Four years before current fiscal year	100	49
Prior	146	299
Revolving Loans	0	0
Total	355	449
Commercial real estate | Domestic | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	22
Prior	62	40
Revolving Loans	0	0
Total	62	62
Commercial real estate | Domestic | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	95
Prior	132	129
Revolving Loans	0	0
Total	132	224
Commercial real estate | Domestic | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Prior	193	47
Revolving Loans	0	0
Total	$ 193	$ 47