Investment Securities - Schedule of Contractual Maturities of Debt Securities (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	$ 6,811
Available for sale, under 1 year, fair value	6,780
Available for sale, 1 to 5 years, amortized cost	24,437
Available for sale, 1 to 5 years, fair value	24,246
Available for sale, 6 to 10 years, amortized cost	8,718
Available for sale, 6 to 10 years, fair value	8,676
Available for sale, over 10 years, amortized cost	8,991
Available for sale, over 10 years, fair value	8,938
Available for sale, amortized cost	48,957	$ 44,853
Available for sale, fair value	48,640	44,526
Held to maturity, amortized cost	52,914	57,117
Investment securities held-to-maturity	46,823	51,503
Direct obligations
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	1,789
Available for sale, under 1 year, fair value	1,788
Available for sale, 1 to 5 years, amortized cost	8,637
Available for sale, 1 to 5 years, fair value	8,527
Available for sale, 6 to 10 years, amortized cost	1,405
Available for sale, 6 to 10 years, fair value	1,414
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	11,831	8,427
Available for sale, fair value	11,729	8,301
Held to maturity, under 1 year, amortized cost	1,548
Held to maturity, under 1 year, fair value	1,525
Held to maturity, 1 to 5 years, amortized cost	4,509
Held to maturity, 1 to 5 years, fair value	4,370
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	10
Held to maturity, over 10 years, fair value	10
Held to maturity, amortized cost	6,091	8,584
Investment securities held-to-maturity	5,928	8,421
Mortgage-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	35
Available for sale, under 1 year, fair value	35
Available for sale, 1 to 5 years, amortized cost	2,062
Available for sale, 1 to 5 years, fair value	2,049
Available for sale, 6 to 10 years, amortized cost	3,219
Available for sale, 6 to 10 years, fair value	3,169
Available for sale, over 10 years, amortized cost	5,892
Available for sale, over 10 years, fair value	5,836
Available for sale, amortized cost	11,208	10,870
Available for sale, fair value	11,089	10,755
Held to maturity, under 1 year, amortized cost	131
Held to maturity, under 1 year, fair value	117
Held to maturity, 1 to 5 years, amortized cost	805
Held to maturity, 1 to 5 years, fair value	741
Held to maturity, 6 to 10 years, amortized cost	4,254
Held to maturity, 6 to 10 years, fair value	3,598
Held to maturity, over 10 years, amortized cost	33,508
Held to maturity, over 10 years, fair value	28,485
Held to maturity, amortized cost	38,698	39,472
Investment securities held-to-maturity	32,941	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	1,824
Available for sale, under 1 year, fair value	1,823
Available for sale, 1 to 5 years, amortized cost	10,699
Available for sale, 1 to 5 years, fair value	10,576
Available for sale, 6 to 10 years, amortized cost	4,624
Available for sale, 6 to 10 years, fair value	4,583
Available for sale, over 10 years, amortized cost	5,892
Available for sale, over 10 years, fair value	5,836
Available for sale, amortized cost	23,039	19,297
Available for sale, fair value	22,818	19,056
Held to maturity, under 1 year, amortized cost	1,679
Held to maturity, under 1 year, fair value	1,642
Held to maturity, 1 to 5 years, amortized cost	5,314
Held to maturity, 1 to 5 years, fair value	5,111
Held to maturity, 6 to 10 years, amortized cost	4,278
Held to maturity, 6 to 10 years, fair value	3,621
Held to maturity, over 10 years, amortized cost	33,518
Held to maturity, over 10 years, fair value	28,495
Held to maturity, amortized cost	44,789	48,056
Investment securities held-to-maturity	38,869	42,629
Mortgage-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	175
Available for sale, under 1 year, fair value	175
Available for sale, 1 to 5 years, amortized cost	284
Available for sale, 1 to 5 years, fair value	284
Available for sale, 6 to 10 years, amortized cost	52
Available for sale, 6 to 10 years, fair value	52
Available for sale, over 10 years, amortized cost	1,450
Available for sale, over 10 years, fair value	1,449
Available for sale, amortized cost	1,961	1,861
Available for sale, fair value	1,960	1,857
Asset-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	334
Available for sale, under 1 year, fair value	332
Available for sale, 1 to 5 years, amortized cost	539
Available for sale, 1 to 5 years, fair value	538
Available for sale, 6 to 10 years, amortized cost	731
Available for sale, 6 to 10 years, fair value	730
Available for sale, over 10 years, amortized cost	564
Available for sale, over 10 years, fair value	565
Available for sale, amortized cost	2,168	2,148
Available for sale, fair value	2,165	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	3,859
Available for sale, under 1 year, fair value	3,837
Available for sale, 1 to 5 years, amortized cost	10,157
Available for sale, 1 to 5 years, fair value	10,094
Available for sale, 6 to 10 years, amortized cost	1,394
Available for sale, 6 to 10 years, fair value	1,390
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	15,410	15,159
Available for sale, fair value	15,321	15,100
Held to maturity, under 1 year, amortized cost	1,837
Held to maturity, under 1 year, fair value	1,809
Held to maturity, 1 to 5 years, amortized cost	2,817
Held to maturity, 1 to 5 years, fair value	2,716
Held to maturity, 6 to 10 years, amortized cost	410
Held to maturity, 6 to 10 years, fair value	388
Held to maturity, over 10 years, amortized cost	0
Held to maturity, over 10 years, fair value	0
Held to maturity, amortized cost	5,064	5,757
Investment securities held-to-maturity	4,913	5,612
Other
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	332
Available for sale, under 1 year, fair value	329
Available for sale, 1 to 5 years, amortized cost	2,199
Available for sale, 1 to 5 years, fair value	2,198
Available for sale, 6 to 10 years, amortized cost	159
Available for sale, 6 to 10 years, fair value	164
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	2,690	2,733
Available for sale, fair value	2,691	2,735
Total non-U.S. debt securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	4,700
Available for sale, under 1 year, fair value	4,673
Available for sale, 1 to 5 years, amortized cost	13,179
Available for sale, 1 to 5 years, fair value	13,114
Available for sale, 6 to 10 years, amortized cost	2,336
Available for sale, 6 to 10 years, fair value	2,336
Available for sale, over 10 years, amortized cost	2,014
Available for sale, over 10 years, fair value	2,014
Available for sale, amortized cost	22,229	21,901
Available for sale, fair value	22,137	21,829
Held to maturity, under 1 year, amortized cost	1,837
Held to maturity, under 1 year, fair value	1,809
Held to maturity, 1 to 5 years, amortized cost	2,817
Held to maturity, 1 to 5 years, fair value	2,716
Held to maturity, 6 to 10 years, amortized cost	410
Held to maturity, 6 to 10 years, fair value	388
Held to maturity, over 10 years, amortized cost	0
Held to maturity, over 10 years, fair value	0
Held to maturity, amortized cost	5,064	5,757
Investment securities held-to-maturity	4,913	5,612
Student loans
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	31
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	14
Available for sale, 6 to 10 years, fair value	14
Available for sale, over 10 years, amortized cost	63
Available for sale, over 10 years, fair value	63
Available for sale, amortized cost	107	113
Available for sale, fair value	108	114
Held to maturity, under 1 year, amortized cost	196
Held to maturity, under 1 year, fair value	192
Held to maturity, 1 to 5 years, amortized cost	336
Held to maturity, 1 to 5 years, fair value	335
Held to maturity, 6 to 10 years, amortized cost	426
Held to maturity, 6 to 10 years, fair value	424
Held to maturity, over 10 years, amortized cost	2,097
Held to maturity, over 10 years, fair value	2,066
Held to maturity, amortized cost	3,055	3,298
Investment securities held-to-maturity	3,017	3,238
Collateralized loan obligations
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	41
Available for sale, under 1 year, fair value	41
Available for sale, 1 to 5 years, amortized cost	283
Available for sale, 1 to 5 years, fair value	282
Available for sale, 6 to 10 years, amortized cost	1,615
Available for sale, 6 to 10 years, fair value	1,615
Available for sale, over 10 years, amortized cost	810
Available for sale, over 10 years, fair value	813
Available for sale, amortized cost	2,749	2,530
Available for sale, fair value	2,751	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	212
Available for sale, over 10 years, fair value	212
Available for sale, amortized cost	212	252
Available for sale, fair value	212	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	5
Held to maturity, over 10 years, fair value	17
Held to maturity, amortized cost	6	6
Investment securities held-to-maturity	24	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	71
Available for sale, under 1 year, fair value	72
Available for sale, 1 to 5 years, amortized cost	373
Available for sale, 1 to 5 years, fair value	373
Available for sale, 6 to 10 years, amortized cost	1,629
Available for sale, 6 to 10 years, fair value	1,629
Available for sale, over 10 years, amortized cost	1,085
Available for sale, over 10 years, fair value	1,088
Available for sale, amortized cost	3,158	2,985
Available for sale, fair value	3,162	2,980
Held to maturity, under 1 year, amortized cost	197
Held to maturity, under 1 year, fair value	199
Held to maturity, 1 to 5 years, amortized cost	336
Held to maturity, 1 to 5 years, fair value	335
Held to maturity, 6 to 10 years, amortized cost	426
Held to maturity, 6 to 10 years, fair value	424
Held to maturity, over 10 years, amortized cost	2,102
Held to maturity, over 10 years, fair value	2,083
Held to maturity, amortized cost	3,061	3,304
Investment securities held-to-maturity	3,041	3,262
State and political subdivisions
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	83
Available for sale, under 1 year, fair value	82
Available for sale, 1 to 5 years, amortized cost	131
Available for sale, 1 to 5 years, fair value	130
Available for sale, 6 to 10 years, amortized cost	129
Available for sale, 6 to 10 years, fair value	128
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	343	356
Available for sale, fair value	340	355
Other U.S. debt securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	133
Available for sale, under 1 year, fair value	130
Available for sale, 1 to 5 years, amortized cost	55
Available for sale, 1 to 5 years, fair value	53
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	188	314
Available for sale, fair value	183	$ 306
Total
Contractual Maturities Of Debt Investment Securities [Line Items]
Held to maturity, under 1 year, amortized cost	3,713
Held to maturity, under 1 year, fair value	3,650
Held to maturity, 1 to 5 years, amortized cost	8,467
Held to maturity, 1 to 5 years, fair value	8,162
Held to maturity, 6 to 10 years, amortized cost	5,114
Held to maturity, 6 to 10 years, fair value	4,433
Held to maturity, over 10 years, amortized cost	35,620
Held to maturity, over 10 years, fair value	30,578
Held to maturity, amortized cost	52,914
Investment securities held-to-maturity	$ 46,823