Investment Securities - Schedule of Contractual Maturities of Debt Securities (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	$ 15,445
Available for sale, under 1 year, fair value	15,440
Available for sale, 1 to 5 years, amortized cost	32,864
Available for sale, 1 to 5 years, fair value	32,941
Available for sale, 6 to 10 years, amortized cost	7,000
Available for sale, 6 to 10 years, fair value	6,977
Available for sale, over 10 years, amortized cost	12,140
Available for sale, over 10 years, fair value	12,086
Available for sale, amortized cost	67,449	$ 59,006
Available for sale, fair value	67,444	58,895
Held to maturity, amortized cost	45,505	47,727
Investment securities held-to-maturity	40,424	41,906
Direct obligations
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	11,077
Available for sale, under 1 year, fair value	11,072
Available for sale, 1 to 5 years, amortized cost	16,060
Available for sale, 1 to 5 years, fair value	16,064
Available for sale, 6 to 10 years, amortized cost	247
Available for sale, 6 to 10 years, fair value	244
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	27,384	23,539
Available for sale, fair value	27,380	23,525
Held to maturity, under 1 year, amortized cost	4,046
Held to maturity, under 1 year, fair value	4,020
Held to maturity, 1 to 5 years, amortized cost	363
Held to maturity, 1 to 5 years, fair value	355
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	4,418	5,417
Investment securities held-to-maturity	4,384	5,362
Mortgage-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	122
Available for sale, under 1 year, fair value	122
Available for sale, 1 to 5 years, amortized cost	1,735
Available for sale, 1 to 5 years, fair value	1,732
Available for sale, 6 to 10 years, amortized cost	2,422
Available for sale, 6 to 10 years, fair value	2,402
Available for sale, over 10 years, amortized cost	8,558
Available for sale, over 10 years, fair value	8,493
Available for sale, amortized cost	12,837	10,699
Available for sale, fair value	12,749	10,566
Held to maturity, under 1 year, amortized cost	148
Held to maturity, under 1 year, fair value	136
Held to maturity, 1 to 5 years, amortized cost	2,352
Held to maturity, 1 to 5 years, fair value	2,148
Held to maturity, 6 to 10 years, amortized cost	2,607
Held to maturity, 6 to 10 years, fair value	2,241
Held to maturity, over 10 years, amortized cost	30,248
Held to maturity, over 10 years, fair value	25,857
Held to maturity, amortized cost	35,355	36,101
Investment securities held-to-maturity	30,382	30,426
Total U.S. Treasury and federal agencies
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	11,199
Available for sale, under 1 year, fair value	11,194
Available for sale, 1 to 5 years, amortized cost	17,795
Available for sale, 1 to 5 years, fair value	17,796
Available for sale, 6 to 10 years, amortized cost	2,669
Available for sale, 6 to 10 years, fair value	2,646
Available for sale, over 10 years, amortized cost	8,558
Available for sale, over 10 years, fair value	8,493
Available for sale, amortized cost	40,221	34,238
Available for sale, fair value	40,129	34,091
Held to maturity, under 1 year, amortized cost	4,194
Held to maturity, under 1 year, fair value	4,156
Held to maturity, 1 to 5 years, amortized cost	2,715
Held to maturity, 1 to 5 years, fair value	2,503
Held to maturity, 6 to 10 years, amortized cost	2,608
Held to maturity, 6 to 10 years, fair value	2,242
Held to maturity, over 10 years, amortized cost	30,256
Held to maturity, over 10 years, fair value	25,865
Held to maturity, amortized cost	39,773	41,518
Investment securities held-to-maturity	34,766	35,788
Mortgage-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	97
Available for sale, under 1 year, fair value	97
Available for sale, 1 to 5 years, amortized cost	458
Available for sale, 1 to 5 years, fair value	459
Available for sale, 6 to 10 years, amortized cost	35
Available for sale, 6 to 10 years, fair value	35
Available for sale, over 10 years, amortized cost	1,876
Available for sale, over 10 years, fair value	1,880
Available for sale, amortized cost	2,466	2,426
Available for sale, fair value	2,471	2,430
Asset-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	243
Available for sale, under 1 year, fair value	243
Available for sale, 1 to 5 years, amortized cost	365
Available for sale, 1 to 5 years, fair value	365
Available for sale, 6 to 10 years, amortized cost	1,109
Available for sale, 6 to 10 years, fair value	1,112
Available for sale, over 10 years, amortized cost	274
Available for sale, over 10 years, fair value	276
Available for sale, amortized cost	1,991	1,865
Available for sale, fair value	1,996	1,868
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	3,413
Available for sale, under 1 year, fair value	3,411
Available for sale, 1 to 5 years, amortized cost	11,475
Available for sale, 1 to 5 years, fair value	11,513
Available for sale, 6 to 10 years, amortized cost	1,139
Available for sale, 6 to 10 years, fair value	1,135
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	16,027	13,954
Available for sale, fair value	16,059	13,939
Held to maturity, under 1 year, amortized cost	1,286
Held to maturity, under 1 year, fair value	1,276
Held to maturity, 1 to 5 years, amortized cost	1,759
Held to maturity, 1 to 5 years, fair value	1,725
Held to maturity, 6 to 10 years, amortized cost	216
Held to maturity, 6 to 10 years, fair value	207
Held to maturity, over 10 years, amortized cost	0
Held to maturity, over 10 years, fair value	0
Held to maturity, amortized cost	3,261	3,673
Investment securities held-to-maturity	3,208	3,607
Other
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	408
Available for sale, under 1 year, fair value	409
Available for sale, 1 to 5 years, amortized cost	2,600
Available for sale, 1 to 5 years, fair value	2,637
Available for sale, 6 to 10 years, amortized cost	81
Available for sale, 6 to 10 years, fair value	83
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	3,089	2,787
Available for sale, fair value	3,129	2,821
Total non-U.S. debt securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	4,161
Available for sale, under 1 year, fair value	4,160
Available for sale, 1 to 5 years, amortized cost	14,898
Available for sale, 1 to 5 years, fair value	14,974
Available for sale, 6 to 10 years, amortized cost	2,364
Available for sale, 6 to 10 years, fair value	2,365
Available for sale, over 10 years, amortized cost	2,150
Available for sale, over 10 years, fair value	2,156
Available for sale, amortized cost	23,573	21,032
Available for sale, fair value	23,655	21,058
Held to maturity, under 1 year, amortized cost	1,286
Held to maturity, under 1 year, fair value	1,276
Held to maturity, 1 to 5 years, amortized cost	1,759
Held to maturity, 1 to 5 years, fair value	1,725
Held to maturity, 6 to 10 years, amortized cost	216
Held to maturity, 6 to 10 years, fair value	207
Held to maturity, over 10 years, amortized cost	0
Held to maturity, over 10 years, fair value	0
Held to maturity, amortized cost	3,261	3,673
Investment securities held-to-maturity	3,208	3,607
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	11
Available for sale, 6 to 10 years, fair value	11
Available for sale, over 10 years, amortized cost	52
Available for sale, over 10 years, fair value	52
Available for sale, amortized cost	86	89
Available for sale, fair value	87	90
Held to maturity, under 1 year, amortized cost	144
Held to maturity, under 1 year, fair value	141
Held to maturity, 1 to 5 years, amortized cost	412
Held to maturity, 1 to 5 years, fair value	412
Held to maturity, 6 to 10 years, amortized cost	263
Held to maturity, 6 to 10 years, fair value	262
Held to maturity, over 10 years, amortized cost	1,652
Held to maturity, over 10 years, fair value	1,635
Held to maturity, amortized cost	2,471	2,536
Investment securities held-to-maturity	2,450	2,511
Collateralized loan obligations
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	24
Available for sale, under 1 year, fair value	24
Available for sale, 1 to 5 years, amortized cost	33
Available for sale, 1 to 5 years, fair value	33
Available for sale, 6 to 10 years, amortized cost	1,956
Available for sale, 6 to 10 years, fair value	1,955
Available for sale, over 10 years, amortized cost	1,380
Available for sale, over 10 years, fair value	1,381
Available for sale, amortized cost	3,393	3,447
Available for sale, fair value	3,393	3,453
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	0
Available for sale, over 10 years, fair value	4
Available for sale, amortized cost	0	1
Available for sale, fair value	4	4
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	91
Total asset-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	47
Available for sale, under 1 year, fair value	48
Available for sale, 1 to 5 years, amortized cost	123
Available for sale, 1 to 5 years, fair value	124
Available for sale, 6 to 10 years, amortized cost	1,967
Available for sale, 6 to 10 years, fair value	1,966
Available for sale, over 10 years, amortized cost	1,432
Available for sale, over 10 years, fair value	1,437
Available for sale, amortized cost	3,569	3,627
Available for sale, fair value	3,575	3,638
Held to maturity, under 1 year, amortized cost	144
Held to maturity, under 1 year, fair value	141
Held to maturity, 1 to 5 years, amortized cost	412
Held to maturity, 1 to 5 years, fair value	412
Held to maturity, 6 to 10 years, amortized cost	263
Held to maturity, 6 to 10 years, fair value	262
Held to maturity, over 10 years, amortized cost	1,652
Held to maturity, over 10 years, fair value	1,635
Held to maturity, amortized cost	2,471	2,536
Investment securities held-to-maturity	2,450	2,511
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	56
Available for sale, fair value	56	56
Other
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	8
Available for sale, under 1 year, fair value	8
Available for sale, 1 to 5 years, amortized cost	22
Available for sale, 1 to 5 years, fair value	21
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	30	53
Available for sale, fair value	29	$ 52
Total
Contractual Maturities Of Debt Investment Securities [Line Items]
Held to maturity, under 1 year, amortized cost	5,624
Held to maturity, under 1 year, fair value	5,573
Held to maturity, 1 to 5 years, amortized cost	4,886
Held to maturity, 1 to 5 years, fair value	4,640
Held to maturity, 6 to 10 years, amortized cost	3,087
Held to maturity, 6 to 10 years, fair value	2,711
Held to maturity, over 10 years, amortized cost	31,908
Held to maturity, over 10 years, fair value	27,500
Held to maturity, amortized cost	45,505
Investment securities held-to-maturity	$ 40,424