Loans and Allowance for Credit Losses - Investments by Credit Quality (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 38,618	$ 36,631
Financing receivable, held-for-sale	17
Current fiscal year	4,740	5,572
Fiscal year before current fiscal year	3,085	3,020
Two years before current fiscal year	2,824	4,685
Three years before current fiscal year	4,556	424
Four years before current fiscal year	403	1,229
Prior	2,372	1,291
Revolving Loans	20,638	20,410
Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Total	33,926	32,024
Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Total	4,028	3,995
Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total	398	304
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total	161	238
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total	105	70
Commercial and Financial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	35,556	33,562
Commercial and Financial | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Total	31,633	29,737
Commercial and Financial | Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Total	3,646	3,546
Commercial and Financial | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total	235	242
Commercial and Financial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total	29	14
Commercial and Financial | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total	13	23
Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	3,062	3,069
Commercial Real Estate | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,293	2,287
Commercial Real Estate | Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Total	382	449
Commercial Real Estate | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total	163	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	92	47
Domestic | Commercial and Financial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	20,448	19,995
Current fiscal year	2,097	2,019
Fiscal year before current fiscal year	746	409
Two years before current fiscal year	324	1,128
Three years before current fiscal year	946	157
Four years before current fiscal year	141	579
Prior	663	146
Revolving Loans	15,531	15,557
Domestic | Commercial and Financial | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Total	17,887	17,479
Current fiscal year	1,566	1,399
Fiscal year before current fiscal year	242	120
Two years before current fiscal year	120	199
Three years before current fiscal year	198	8
Four years before current fiscal year	8	272
Prior	276	5
Revolving Loans	15,477	15,476
Domestic | Commercial and Financial | Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,366	2,309
Current fiscal year	523	615
Fiscal year before current fiscal year	473	285
Two years before current fiscal year	204	747
Three years before current fiscal year	637	149
Four years before current fiscal year	104	291
Prior	371	141
Revolving Loans	54	81
Domestic | Commercial and Financial | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total	167	184
Current fiscal year	0	0
Fiscal year before current fiscal year	26	4
Two years before current fiscal year	0	164
Three years before current fiscal year	96	0
Four years before current fiscal year	29	16
Prior	16	0
Revolving Loans	0	0
Domestic | Commercial and Financial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total	15	23
Current fiscal year	0	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
Domestic | Commercial and Financial | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total	13
Current fiscal year	8
Fiscal year before current fiscal year	5
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
Domestic | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	3,062	3,069
Current fiscal year	39	216
Fiscal year before current fiscal year	216	520
Two years before current fiscal year	520	529
Three years before current fiscal year	531	150
Four years before current fiscal year	149	541
Prior	1,607	1,113
Revolving Loans	0	0
Domestic | Commercial Real Estate | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,293	2,287
Current fiscal year	39	216
Fiscal year before current fiscal year	216	500
Two years before current fiscal year	500	498
Three years before current fiscal year	465	100
Four years before current fiscal year	100	375
Prior	973	598
Revolving Loans	0	0
Domestic | Commercial Real Estate | Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Total	382	449
Current fiscal year	0	0
Fiscal year before current fiscal year	0	20
Two years before current fiscal year	20	31
Three years before current fiscal year	66	50
Four years before current fiscal year	49	49
Prior	247	299
Revolving Loans	0	0
Domestic | Commercial Real Estate | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total	163	62
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	163	40
Revolving Loans	0	0
Domestic | Commercial Real Estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total	132	224
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
Domestic | Commercial Real Estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total	92	47
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	92	47
Revolving Loans	0	0
Domestic | Fund Finance
Financing Receivable, Credit Quality Indicator [Line Items]
Overdrafts	3,720	$ 2,270
Domestic | Fund Finance | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Overdrafts	3,570
Domestic | Fund Finance | Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Overdrafts	$ 150