Investment Securities - Schedule of Contractual Maturities of Debt Securities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	$ 12,199
Available for sale, under 1 year, fair value	12,199
Available for sale, 1 to 5 years, amortized cost	28,684
Available for sale, 1 to 5 years, fair value	28,699
Available for sale, 6 to 10 years, amortized cost	8,093
Available for sale, 6 to 10 years, fair value	8,060
Available for sale, over 10 years, amortized cost	10,030
Available for sale, over 10 years, fair value	9,937
Available for sale, amortized cost	59,006	$ 44,853
Available-for-sale investment securities:	58,895	44,526
Held to maturity, amortized cost	47,727	57,117
Investment securities held-to-maturity	41,906	51,503
US Treasury and federal agencies, direct obligations
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	8,619
Available for sale, under 1 year, fair value	8,625
Available for sale, 1 to 5 years, amortized cost	13,485
Available for sale, 1 to 5 years, fair value	13,474
Available for sale, 6 to 10 years, amortized cost	1,435
Available for sale, 6 to 10 years, fair value	1,426
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	23,539	8,427
Available-for-sale investment securities:	23,525	8,301
Held to maturity, under 1 year, amortized cost	4,557
Held to maturity, under 1 year, fair value	4,521
Held to maturity, 1 to 5 years, amortized cost	851
Held to maturity, 1 to 5 years, fair value	832
Held to maturity, 6 to 10 years, amortized cost	1
Held to maturity, 6 to 10 years, fair value	1
Held to maturity, over 10 years, amortized cost	8
Held to maturity, over 10 years, fair value	8
Held to maturity, amortized cost	5,417	8,584
Investment securities held-to-maturity	5,362	8,421
US Treasury and federal agencies, mortgage-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	49
Available for sale, 1 to 5 years, amortized cost	1,824
Available for sale, 1 to 5 years, fair value	1,819
Available for sale, 6 to 10 years, amortized cost	2,517
Available for sale, 6 to 10 years, fair value	2,493
Available for sale, over 10 years, amortized cost	6,309
Available for sale, over 10 years, fair value	6,205
Available for sale, amortized cost	10,699	10,870
Available-for-sale investment securities:	10,566	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	1,711
Held to maturity, 1 to 5 years, fair value	1,559
Held to maturity, 6 to 10 years, amortized cost	3,308
Held to maturity, 6 to 10 years, fair value	2,788
Held to maturity, over 10 years, amortized cost	30,948
Held to maturity, over 10 years, fair value	25,959
Held to maturity, amortized cost	36,101	39,472
Investment securities held-to-maturity	30,426	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	8,668
Available for sale, under 1 year, fair value	8,674
Available for sale, 1 to 5 years, amortized cost	15,309
Available for sale, 1 to 5 years, fair value	15,293
Available for sale, 6 to 10 years, amortized cost	3,952
Available for sale, 6 to 10 years, fair value	3,919
Available for sale, over 10 years, amortized cost	6,309
Available for sale, over 10 years, fair value	6,205
Available for sale, amortized cost	34,238	19,297
Available-for-sale investment securities:	34,091	19,056
Held to maturity, under 1 year, amortized cost	4,691
Held to maturity, under 1 year, fair value	4,641
Held to maturity, 1 to 5 years, amortized cost	2,562
Held to maturity, 1 to 5 years, fair value	2,391
Held to maturity, 6 to 10 years, amortized cost	3,309
Held to maturity, 6 to 10 years, fair value	2,789
Held to maturity, over 10 years, amortized cost	30,956
Held to maturity, over 10 years, fair value	25,967
Held to maturity, amortized cost	41,518	48,056
Investment securities held-to-maturity	35,788	42,629
Non-U.S. debt securities, mortgage-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	58
Available for sale, under 1 year, fair value	58
Available for sale, 1 to 5 years, amortized cost	427
Available for sale, 1 to 5 years, fair value	427
Available for sale, 6 to 10 years, amortized cost	38
Available for sale, 6 to 10 years, fair value	38
Available for sale, over 10 years, amortized cost	1,903
Available for sale, over 10 years, fair value	1,907
Available for sale, amortized cost	2,426	1,861
Available-for-sale investment securities:	2,430	1,857
Non-U.S. debt securities, asset-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	276
Available for sale, under 1 year, fair value	276
Available for sale, 1 to 5 years, amortized cost	279
Available for sale, 1 to 5 years, fair value	279
Available for sale, 6 to 10 years, amortized cost	1,005
Available for sale, 6 to 10 years, fair value	1,007
Available for sale, over 10 years, amortized cost	305
Available for sale, over 10 years, fair value	306
Available for sale, amortized cost	1,865	2,148
Available-for-sale investment securities:	1,868	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	2,706
Available for sale, under 1 year, fair value	2,700
Available for sale, 1 to 5 years, amortized cost	10,138
Available for sale, 1 to 5 years, fair value	10,136
Available for sale, 6 to 10 years, amortized cost	1,110
Available for sale, 6 to 10 years, fair value	1,103
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	13,954	15,159
Available-for-sale investment securities:	13,939	15,100
Held to maturity, under 1 year, amortized cost	1,409
Held to maturity, under 1 year, fair value	1,397
Held to maturity, 1 to 5 years, amortized cost	2,044
Held to maturity, 1 to 5 years, fair value	1,998
Held to maturity, 6 to 10 years, amortized cost	220
Held to maturity, 6 to 10 years, fair value	212
Held to maturity, over 10 years, amortized cost	0
Held to maturity, over 10 years, fair value	0
Held to maturity, amortized cost	3,673	5,757
Investment securities held-to-maturity	3,607	5,612
Non-U.S. debt securities, other
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	371
Available for sale, under 1 year, fair value	371
Available for sale, 1 to 5 years, amortized cost	2,314
Available for sale, 1 to 5 years, fair value	2,346
Available for sale, 6 to 10 years, amortized cost	102
Available for sale, 6 to 10 years, fair value	104
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	2,787	2,733
Available-for-sale investment securities:	2,821	2,735
Total non-U.S. debt securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	3,411
Available for sale, under 1 year, fair value	3,405
Available for sale, 1 to 5 years, amortized cost	13,158
Available for sale, 1 to 5 years, fair value	13,188
Available for sale, 6 to 10 years, amortized cost	2,255
Available for sale, 6 to 10 years, fair value	2,252
Available for sale, over 10 years, amortized cost	2,208
Available for sale, over 10 years, fair value	2,213
Available for sale, amortized cost	21,032	21,901
Available-for-sale investment securities:	21,058	21,829
Held to maturity, under 1 year, amortized cost	1,409
Held to maturity, under 1 year, fair value	1,397
Held to maturity, 1 to 5 years, amortized cost	2,044
Held to maturity, 1 to 5 years, fair value	1,998
Held to maturity, 6 to 10 years, amortized cost	220
Held to maturity, 6 to 10 years, fair value	212
Held to maturity, over 10 years, amortized cost	0
Held to maturity, over 10 years, fair value	0
Held to maturity, amortized cost	3,673	5,757
Investment securities held-to-maturity	3,607	5,612
Asset-backed securities, student loans
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	23
Available for sale, under 1 year, fair value	24
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	12
Available for sale, 6 to 10 years, fair value	12
Available for sale, over 10 years, amortized cost	54
Available for sale, over 10 years, fair value	54
Available for sale, amortized cost	89	113
Available-for-sale investment securities:	90	114
Held to maturity, under 1 year, amortized cost	149
Held to maturity, under 1 year, fair value	147
Held to maturity, 1 to 5 years, amortized cost	310
Held to maturity, 1 to 5 years, fair value	309
Held to maturity, 6 to 10 years, amortized cost	380
Held to maturity, 6 to 10 years, fair value	379
Held to maturity, over 10 years, amortized cost	1,697
Held to maturity, over 10 years, fair value	1,676
Held to maturity, amortized cost	2,536	3,298
Investment securities held-to-maturity	2,511	3,238
Asset-backed securities, collateralized loan obligations
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	37
Available for sale, under 1 year, fair value	37
Available for sale, 1 to 5 years, amortized cost	78
Available for sale, 1 to 5 years, fair value	78
Available for sale, 6 to 10 years, amortized cost	1,874
Available for sale, 6 to 10 years, fair value	1,877
Available for sale, over 10 years, amortized cost	1,458
Available for sale, over 10 years, fair value	1,461
Available for sale, amortized cost	3,447	90
Available-for-sale investment securities:	3,453	90
Asset-backed securities, 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	1
Available for sale, over 10 years, fair value	4
Available for sale, amortized cost	1	252
Available-for-sale investment securities:	4	249
Held to maturity, amortized cost	0	6
Investment securities held-to-maturity	0	24
Asset-backed securities, 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	2,530
Available-for-sale investment securities:	91	2,527
Total asset-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	60
Available for sale, under 1 year, fair value	61
Available for sale, 1 to 5 years, amortized cost	168
Available for sale, 1 to 5 years, fair value	169
Available for sale, 6 to 10 years, amortized cost	1,886
Available for sale, 6 to 10 years, fair value	1,889
Available for sale, over 10 years, amortized cost	1,513
Available for sale, over 10 years, fair value	1,519
Available for sale, amortized cost	3,627	2,985
Available-for-sale investment securities:	3,638	2,980
Held to maturity, under 1 year, amortized cost	149
Held to maturity, under 1 year, fair value	147
Held to maturity, 1 to 5 years, amortized cost	310
Held to maturity, 1 to 5 years, fair value	309
Held to maturity, 6 to 10 years, amortized cost	380
Held to maturity, 6 to 10 years, fair value	379
Held to maturity, over 10 years, amortized cost	1,697
Held to maturity, over 10 years, fair value	1,676
Held to maturity, amortized cost	2,536	3,304
Investment securities held-to-maturity	2,511	3,262
State and political subdivisions
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	30
Available for sale, under 1 year, fair value	30
Available for sale, 1 to 5 years, amortized cost	26
Available for sale, 1 to 5 years, fair value	26
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	56	356
Available-for-sale investment securities:	56	355
Other U.S. debt securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	30
Available for sale, under 1 year, fair value	29
Available for sale, 1 to 5 years, amortized cost	23
Available for sale, 1 to 5 years, fair value	23
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	53	314
Available-for-sale investment securities:	52	$ 306
Total HTM and Collateralized Obligations
Contractual Maturities Of Debt Investment Securities [Line Items]
Held to maturity, under 1 year, amortized cost	6,249
Held to maturity, under 1 year, fair value	6,185
Held to maturity, 1 to 5 years, amortized cost	4,916
Held to maturity, 1 to 5 years, fair value	4,698
Held to maturity, 6 to 10 years, amortized cost	3,909
Held to maturity, 6 to 10 years, fair value	3,380
Held to maturity, over 10 years, amortized cost	32,653
Held to maturity, over 10 years, fair value	27,643
Held to maturity, amortized cost	47,727
Investment securities held-to-maturity	$ 41,906