Investment Securities - Schedule of Gross Pre-Tax Unrealized Losses on Investment Securities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	$ 6,383	$ 19,429
Available for sale, gross unrealized losses less than 12 months	16	368
Available for sale, fair value 12 months or longer	22,572	18,093
Available for sale, gross unrealized losses 12 months or longer	520	924
Available for sale, fair value total	28,955	37,522
Available for sale, gross unrealized losses total	536	1,293
US Treasury and federal agencies, direct obligations
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	333	1,337
Available for sale, gross unrealized losses less than 12 months	2	15
Available for sale, fair value 12 months or longer	5,416	5,745
Available for sale, gross unrealized losses 12 months or longer	163	246
Available for sale, fair value total	5,749	7,082
Available for sale, gross unrealized losses total	165	261
US Treasury and federal agencies, mortgage-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	961	5,524
Available for sale, gross unrealized losses less than 12 months	6	130
Available for sale, fair value 12 months or longer	6,512	2,815
Available for sale, gross unrealized losses 12 months or longer	158	130
Available for sale, fair value total	7,473	8,339
Available for sale, gross unrealized losses total	164	260
Total U.S. Treasury and federal agencies
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	1,294	6,861
Available for sale, gross unrealized losses less than 12 months	8	145
Available for sale, fair value 12 months or longer	11,928	8,560
Available for sale, gross unrealized losses 12 months or longer	321	376
Available for sale, fair value total	13,222	15,421
Available for sale, gross unrealized losses total	329	521
Non-U.S. debt securities, mortgage-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	424	1,278
Available for sale, gross unrealized losses less than 12 months	1	15
Available for sale, fair value 12 months or longer	719	272
Available for sale, gross unrealized losses 12 months or longer	6	4
Available for sale, fair value total	1,143	1,550
Available for sale, gross unrealized losses total	7	19
Non-U.S. debt securities, asset-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	358	859
Available for sale, gross unrealized losses less than 12 months	0	11
Available for sale, fair value 12 months or longer	1,052	765
Available for sale, gross unrealized losses 12 months or longer	13	16
Available for sale, fair value total	1,410	1,624
Available for sale, gross unrealized losses total	13	27
Non-U.S. sovereign, supranational and non-U.S. agency
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	3,972	6,750
Available for sale, gross unrealized losses less than 12 months	7	108
Available for sale, fair value 12 months or longer	5,788	5,800
Available for sale, gross unrealized losses 12 months or longer	125	316
Available for sale, fair value total	9,760	12,550
Available for sale, gross unrealized losses total	132	424
Non-U.S. debt securities, other
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	50	771
Available for sale, gross unrealized losses less than 12 months	0	27
Available for sale, fair value 12 months or longer	893	1,233
Available for sale, gross unrealized losses 12 months or longer	37	137
Available for sale, fair value total	943	2,004
Available for sale, gross unrealized losses total	37	164
Total non-U.S. debt securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	4,804	9,658
Available for sale, gross unrealized losses less than 12 months	8	161
Available for sale, fair value 12 months or longer	8,452	8,070
Available for sale, gross unrealized losses 12 months or longer	181	473
Available for sale, fair value total	13,256	17,728
Available for sale, gross unrealized losses total	189	634
Asset-backed securities, student loans
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months		89
Available for sale, gross unrealized losses less than 12 months		1
Available for sale, fair value 12 months or longer		0
Available for sale, gross unrealized losses 12 months or longer		0
Available for sale, fair value total		89
Available for sale, gross unrealized losses total		1
Asset-backed securities, collateralized loan obligations
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	183	1,577
Available for sale, gross unrealized losses less than 12 months	0	27
Available for sale, fair value 12 months or longer	1,605	710
Available for sale, gross unrealized losses 12 months or longer	6	12
Available for sale, fair value total	1,788	2,287
Available for sale, gross unrealized losses total	6	39
Asset-backed securities, non-agency CMBS and RMBS
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	35	193
Available for sale, gross unrealized losses less than 12 months	0	6
Available for sale, fair value 12 months or longer	180	3
Available for sale, gross unrealized losses 12 months or longer	3	0
Available for sale, fair value total	215	196
Available for sale, gross unrealized losses total	3	6
Asset-backed securities, other
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months		88
Available for sale, gross unrealized losses less than 12 months		2
Available for sale, fair value 12 months or longer		0
Available for sale, gross unrealized losses 12 months or longer		0
Available for sale, fair value total		88
Available for sale, gross unrealized losses total		2
Total asset-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	218	1,947
Available for sale, gross unrealized losses less than 12 months	0	36
Available for sale, fair value 12 months or longer	1,785	713
Available for sale, gross unrealized losses 12 months or longer	9	12
Available for sale, fair value total	2,003	2,660
Available for sale, gross unrealized losses total	9	48
State and political subdivisions
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	64	669
Available for sale, gross unrealized losses less than 12 months	0	12
Available for sale, fair value 12 months or longer	104	42
Available for sale, gross unrealized losses 12 months or longer	1	5
Available for sale, fair value total	168	711
Available for sale, gross unrealized losses total	1	17
Other U.S. debt securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	3	294
Available for sale, gross unrealized losses less than 12 months	0	15
Available for sale, fair value 12 months or longer	303	708
Available for sale, gross unrealized losses 12 months or longer	8	58
Available for sale, fair value total	306	1,002
Available for sale, gross unrealized losses total	$ 8	$ 73

Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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