Loans and Allowance for Credit Losses - Amortized Cost Basis (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
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
Loans, gross, excluding loans classified as held-for-sale	38,618	36,631
Financing receivable, accrued interest, before allowance for credit loss	290	318
Financing receivable, held-for-sale	17
Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	33,926	32,024
Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	4,028	3,995
Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	398	304
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	161	238
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	105	70
Commercial and Financial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	35,556	33,562
Commercial and Financial \| Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	31,633	29,737
Commercial and Financial \| Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	3,646	3,546
Commercial and Financial \| Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	235	242
Commercial and Financial \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	29	14
Commercial and Financial \| Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	13	23
Commercial and Financial \| Domestic
Financing Receivable, Credit Quality Indicator [Line Items]
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
Loans, gross, excluding loans classified as held-for-sale	20,448	19,995
Commercial and Financial \| Domestic \| Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
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
Loans, gross, excluding loans classified as held-for-sale	17,887	17,479
Commercial and Financial \| Domestic \| Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
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
Loans, gross, excluding loans classified as held-for-sale	2,366	2,309
Commercial and Financial \| Domestic \| Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
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
Loans, gross, excluding loans classified as held-for-sale	167	184
Commercial and Financial \| Domestic \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
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
Loans, gross, excluding loans classified as held-for-sale	15	23
Commercial and Financial \| Domestic \| Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
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
Loans, gross, excluding loans classified as held-for-sale	13
Commercial and Financial \| Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	2,604	3,337
Fiscal year before current fiscal year	2,123	2,091
Two years before current fiscal year	1,980	3,028
Three years before current fiscal year	3,079	117
Four years before current fiscal year	113	109
Prior	102	32
Revolving Loans	5,107	4,853
Loans, gross, excluding loans classified as held-for-sale	15,108	13,567
Commercial and Financial \| Non-U.S. \| Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	2,328	2,943
Fiscal year before current fiscal year	1,853	1,956
Two years before current fiscal year	1,853	2,518
Three years before current fiscal year	2,633	0
Four years before current fiscal year	0	0
Prior	0	0
Revolving Loans	5,079	4,841
Loans, gross, excluding loans classified as held-for-sale	13,746	12,258
Commercial and Financial \| Non-U.S. \| Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	276	394
Fiscal year before current fiscal year	270	135
Two years before current fiscal year	127	481
Three years before current fiscal year	378	88
Four years before current fiscal year	113	109
Prior	88	18
Revolving Loans	28	12
Loans, gross, excluding loans classified as held-for-sale	1,280	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	68	29
Four years before current fiscal year	0	0
Prior	0	0
Revolving Loans	0	0
Loans, gross, excluding loans classified as held-for-sale	68	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
Loans, gross, excluding loans classified as held-for-sale	14	14
Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	3,062	3,069
Commercial real estate \| Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	2,293	2,287
Commercial real estate \| Speculative
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	382	449
Commercial real estate \| Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	163	62
Commercial real estate \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	132	224
Commercial real estate \| Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross, excluding loans classified as held-for-sale	92	47
Commercial real estate \| Domestic
Financing Receivable, Credit Quality Indicator [Line Items]
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
Loans, gross, excluding loans classified as held-for-sale	3,062	3,069
Commercial real estate \| Domestic \| Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
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
Loans, gross, excluding loans classified as held-for-sale	2,293	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	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
Loans, gross, excluding loans classified as held-for-sale	382	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	163	40
Revolving Loans	0	0
Loans, gross, excluding loans classified as held-for-sale	163	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
Loans, gross, excluding loans classified as held-for-sale	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	92	47
Revolving Loans	0	0
Loans, gross, excluding loans classified as held-for-sale	$ 92	$ 47

Financing Receivable, Excluding Accrued Interest, Before Allowance For Credit Loss, Excluding Held For Sale Receivables

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- Definition

Amount, before allowance for credit loss, of accrued interest on financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
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Amortized cost excluding accrued interest, of financing receivable originated more than five years prior to current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
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-Section 55
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Amortized cost excluding accrued interest, of financing receivable that can be withdrawn, repaid, and redrawn.

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Amortized cost excluding accrued interest, of financing receivable originated four years prior to current fiscal year. Excludes net investment in lease.

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Amortized cost excluding accrued interest, of financing receivable originated three years prior to current fiscal year. Excludes net investment in lease.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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