Investment Securities - Schedule of Contractual Maturities of Debt Securities (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	$ 7,477
Available for sale, under 1 year, fair value	7,458
Available for sale, 1 to 5 years, amortized cost	29,937
Available for sale, 1 to 5 years, fair value	29,723
Available for sale, 6 to 10 years, amortized cost	10,321
Available for sale, 6 to 10 years, fair value	10,285
Available for sale, over 10 years, amortized cost	9,355
Available for sale, over 10 years, fair value	9,289
Available for sale, amortized cost	57,090	$ 44,853
Available for sale, fair value	56,755	44,526
Held to maturity, amortized cost	51,051	57,117
Investment securities held-to-maturity	44,916	51,503
Direct obligations
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	2,782
Available for sale, under 1 year, fair value	2,780
Available for sale, 1 to 5 years, amortized cost	12,853
Available for sale, 1 to 5 years, fair value	12,747
Available for sale, 6 to 10 years, amortized cost	3,064
Available for sale, 6 to 10 years, fair value	3,062
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	18,699	8,427
Available for sale, fair value	18,589	8,301
Held to maturity, under 1 year, amortized cost	2,803
Held to maturity, under 1 year, fair value	2,762
Held to maturity, 1 to 5 years, amortized cost	3,284
Held to maturity, 1 to 5 years, fair value	3,184
Held to maturity, 6 to 10 years, amortized cost	24
Held to maturity, 6 to 10 years, fair value	23
Held to maturity, over 10 years, amortized cost	8
Held to maturity, over 10 years, fair value	8
Held to maturity, amortized cost	6,119	8,584
Investment securities held-to-maturity	5,977	8,421
Mortgage-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	36
Available for sale, under 1 year, fair value	35
Available for sale, 1 to 5 years, amortized cost	2,065
Available for sale, 1 to 5 years, fair value	2,058
Available for sale, 6 to 10 years, amortized cost	2,971
Available for sale, 6 to 10 years, fair value	2,943
Available for sale, over 10 years, amortized cost	5,985
Available for sale, over 10 years, fair value	5,913
Available for sale, amortized cost	11,057	10,870
Available for sale, fair value	10,949	10,755
Held to maturity, under 1 year, amortized cost	134
Held to maturity, under 1 year, fair value	120
Held to maturity, 1 to 5 years, amortized cost	994
Held to maturity, 1 to 5 years, fair value	907
Held to maturity, 6 to 10 years, amortized cost	4,051
Held to maturity, 6 to 10 years, fair value	3,415
Held to maturity, over 10 years, amortized cost	32,658
Held to maturity, over 10 years, fair value	27,551
Held to maturity, amortized cost	37,837	39,472
Investment securities held-to-maturity	31,993	34,208
Total U.S. Treasury and federal agencies
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	2,818
Available for sale, under 1 year, fair value	2,815
Available for sale, 1 to 5 years, amortized cost	14,918
Available for sale, 1 to 5 years, fair value	14,805
Available for sale, 6 to 10 years, amortized cost	6,035
Available for sale, 6 to 10 years, fair value	6,005
Available for sale, over 10 years, amortized cost	5,985
Available for sale, over 10 years, fair value	5,913
Available for sale, amortized cost	29,756	19,297
Available for sale, fair value	29,538	19,056
Held to maturity, under 1 year, amortized cost	2,937
Held to maturity, under 1 year, fair value	2,882
Held to maturity, 1 to 5 years, amortized cost	4,278
Held to maturity, 1 to 5 years, fair value	4,091
Held to maturity, 6 to 10 years, amortized cost	4,075
Held to maturity, 6 to 10 years, fair value	3,438
Held to maturity, over 10 years, amortized cost	32,666
Held to maturity, over 10 years, fair value	27,559
Held to maturity, amortized cost	43,956	48,056
Investment securities held-to-maturity	37,970	42,629
Mortgage-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	126
Available for sale, under 1 year, fair value	126
Available for sale, 1 to 5 years, amortized cost	355
Available for sale, 1 to 5 years, fair value	355
Available for sale, 6 to 10 years, amortized cost	49
Available for sale, 6 to 10 years, fair value	49
Available for sale, over 10 years, amortized cost	1,825
Available for sale, over 10 years, fair value	1,826
Available for sale, amortized cost	2,355	1,861
Available for sale, fair value	2,356	1,857
Asset-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	294
Available for sale, under 1 year, fair value	293
Available for sale, 1 to 5 years, amortized cost	540
Available for sale, 1 to 5 years, fair value	540
Available for sale, 6 to 10 years, amortized cost	977
Available for sale, 6 to 10 years, fair value	978
Available for sale, over 10 years, amortized cost	424
Available for sale, over 10 years, fair value	427
Available for sale, amortized cost	2,235	2,148
Available for sale, fair value	2,238	2,137
Non-U.S. sovereign, supranational and non-U.S. agency
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	3,641
Available for sale, under 1 year, fair value	3,626
Available for sale, 1 to 5 years, amortized cost	11,156
Available for sale, 1 to 5 years, fair value	11,063
Available for sale, 6 to 10 years, amortized cost	1,483
Available for sale, 6 to 10 years, fair value	1,472
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	16,280	15,159
Available for sale, fair value	16,161	15,100
Held to maturity, under 1 year, amortized cost	1,139
Held to maturity, under 1 year, fair value	1,123
Held to maturity, 1 to 5 years, amortized cost	2,830
Held to maturity, 1 to 5 years, fair value	2,725
Held to maturity, 6 to 10 years, amortized cost	304
Held to maturity, 6 to 10 years, fair value	284
Held to maturity, over 10 years, amortized cost	0
Held to maturity, over 10 years, fair value	0
Held to maturity, amortized cost	4,273	5,757
Investment securities held-to-maturity	4,132	5,612
Other
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	347
Available for sale, under 1 year, fair value	346
Available for sale, 1 to 5 years, amortized cost	2,564
Available for sale, 1 to 5 years, fair value	2,560
Available for sale, 6 to 10 years, amortized cost	135
Available for sale, 6 to 10 years, fair value	138
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	3,046	2,733
Available for sale, fair value	3,044	2,735
Total non-U.S. debt securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	4,408
Available for sale, under 1 year, fair value	4,391
Available for sale, 1 to 5 years, amortized cost	14,615
Available for sale, 1 to 5 years, fair value	14,518
Available for sale, 6 to 10 years, amortized cost	2,644
Available for sale, 6 to 10 years, fair value	2,637
Available for sale, over 10 years, amortized cost	2,249
Available for sale, over 10 years, fair value	2,253
Available for sale, amortized cost	23,916	21,901
Available for sale, fair value	23,799	21,829
Held to maturity, under 1 year, amortized cost	1,139
Held to maturity, under 1 year, fair value	1,123
Held to maturity, 1 to 5 years, amortized cost	2,830
Held to maturity, 1 to 5 years, fair value	2,725
Held to maturity, 6 to 10 years, amortized cost	304
Held to maturity, 6 to 10 years, fair value	284
Held to maturity, over 10 years, amortized cost	0
Held to maturity, over 10 years, fair value	0
Held to maturity, amortized cost	4,273	5,757
Investment securities held-to-maturity	4,132	5,612
Student loans
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	27
Available for sale, under 1 year, fair value	28
Available for sale, 1 to 5 years, amortized cost	0
Available for sale, 1 to 5 years, fair value	0
Available for sale, 6 to 10 years, amortized cost	13
Available for sale, 6 to 10 years, fair value	13
Available for sale, over 10 years, amortized cost	59
Available for sale, over 10 years, fair value	60
Available for sale, amortized cost	99	113
Available for sale, fair value	101	114
Held to maturity, under 1 year, amortized cost	179
Held to maturity, under 1 year, fair value	176
Held to maturity, 1 to 5 years, amortized cost	307
Held to maturity, 1 to 5 years, fair value	305
Held to maturity, 6 to 10 years, amortized cost	451
Held to maturity, 6 to 10 years, fair value	450
Held to maturity, over 10 years, amortized cost	1,880
Held to maturity, over 10 years, fair value	1,861
Held to maturity, amortized cost	2,817	3,298
Investment securities held-to-maturity	2,792	3,238
Collateralized loan obligations
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	22
Available for sale, under 1 year, fair value	22
Available for sale, 1 to 5 years, amortized cost	154
Available for sale, 1 to 5 years, fair value	155
Available for sale, 6 to 10 years, amortized cost	1,506
Available for sale, 6 to 10 years, fair value	1,508
Available for sale, over 10 years, amortized cost	925
Available for sale, over 10 years, fair value	927
Available for sale, amortized cost	2,607	2,530
Available for sale, fair value	2,612	2,527
Non-agency CMBS and RMBS
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	0
Available for sale, under 1 year, fair value	0
Available for sale, 1 to 5 years, amortized cost	0
Available for sale, 1 to 5 years, fair value	0
Available for sale, 6 to 10 years, amortized cost	0
Available for sale, 6 to 10 years, fair value	0
Available for sale, over 10 years, amortized cost	137
Available for sale, over 10 years, fair value	136
Available for sale, amortized cost	137	252
Available for sale, fair value	136	249
Held to maturity, under 1 year, amortized cost	1
Held to maturity, under 1 year, fair value	7
Held to maturity, 1 to 5 years, amortized cost	0
Held to maturity, 1 to 5 years, fair value	0
Held to maturity, 6 to 10 years, amortized cost	0
Held to maturity, 6 to 10 years, fair value	0
Held to maturity, over 10 years, amortized cost	4
Held to maturity, over 10 years, fair value	15
Held to maturity, amortized cost	5	6
Investment securities held-to-maturity	22	24
Other
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	0
Available for sale, under 1 year, fair value	0
Available for sale, 1 to 5 years, amortized cost	90
Available for sale, 1 to 5 years, fair value	91
Available for sale, 6 to 10 years, amortized cost	0
Available for sale, 6 to 10 years, fair value	0
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	90	90
Available for sale, fair value	91	90
Total asset-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	49
Available for sale, under 1 year, fair value	50
Available for sale, 1 to 5 years, amortized cost	244
Available for sale, 1 to 5 years, fair value	246
Available for sale, 6 to 10 years, amortized cost	1,519
Available for sale, 6 to 10 years, fair value	1,521
Available for sale, over 10 years, amortized cost	1,121
Available for sale, over 10 years, fair value	1,123
Available for sale, amortized cost	2,933	2,985
Available for sale, fair value	2,940	2,980
Held to maturity, under 1 year, amortized cost	180
Held to maturity, under 1 year, fair value	183
Held to maturity, 1 to 5 years, amortized cost	307
Held to maturity, 1 to 5 years, fair value	305
Held to maturity, 6 to 10 years, amortized cost	451
Held to maturity, 6 to 10 years, fair value	450
Held to maturity, over 10 years, amortized cost	1,884
Held to maturity, over 10 years, fair value	1,876
Held to maturity, amortized cost	2,822	3,304
Investment securities held-to-maturity	2,814	3,262
State and political subdivisions
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	107
Available for sale, under 1 year, fair value	107
Available for sale, 1 to 5 years, amortized cost	110
Available for sale, 1 to 5 years, fair value	108
Available for sale, 6 to 10 years, amortized cost	123
Available for sale, 6 to 10 years, fair value	122
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	340	356
Available for sale, fair value	337	355
Other U.S. debt securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	95
Available for sale, under 1 year, fair value	95
Available for sale, 1 to 5 years, amortized cost	50
Available for sale, 1 to 5 years, fair value	46
Available for sale, 6 to 10 years, amortized cost	0
Available for sale, 6 to 10 years, fair value	0
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	145	314
Available for sale, fair value	141	$ 306
Total
Contractual Maturities Of Debt Investment Securities [Line Items]
Held to maturity, under 1 year, amortized cost	4,256
Held to maturity, under 1 year, fair value	4,188
Held to maturity, 1 to 5 years, amortized cost	7,415
Held to maturity, 1 to 5 years, fair value	7,121
Held to maturity, 6 to 10 years, amortized cost	4,830
Held to maturity, 6 to 10 years, fair value	4,172
Held to maturity, over 10 years, amortized cost	34,550
Held to maturity, over 10 years, fair value	29,435
Held to maturity, amortized cost	51,051
Investment securities held-to-maturity	$ 44,916