Investment Securities - Schedule of Contractual Maturities of Debt Securities (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	$ 9,786
Available for sale, under 1 year, fair value	9,792
Available for sale, 1 to 5 years, amortized cost	39,920
Available for sale, 1 to 5 years, fair value	39,881
Available for sale, 6 to 10 years, amortized cost	3,502
Available for sale, 6 to 10 years, fair value	3,497
Available for sale, over 10 years, amortized cost	18,461
Available for sale, over 10 years, fair value	18,475
Available for sale, amortized cost	71,669	$ 66,973
Available for sale, fair value	71,645	67,154
Held to maturity, under 1 year, amortized cost	1,383
Held to maturity, under 1 year, fair value	1,361
Held to maturity, 1 to 5 years, amortized cost	5,794
Held to maturity, 1 to 5 years, fair value	5,385
Held to maturity, 6 to 10 years, amortized cost	1,517
Held to maturity, 6 to 10 years, fair value	1,439
Held to maturity, over 10 years, amortized cost	28,038
Held to maturity, over 10 years, fair value	24,375
Held to maturity, amortized cost	36,732	38,171
Investment securities held-to-maturity	32,560	34,166
Total U.S. Treasury and federal agencies
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	4,636
Available for sale, under 1 year, fair value	4,639
Available for sale, 1 to 5 years, amortized cost	22,111
Available for sale, 1 to 5 years, fair value	22,127
Available for sale, 6 to 10 years, amortized cost	729
Available for sale, 6 to 10 years, fair value	723
Available for sale, over 10 years, amortized cost	14,022
Available for sale, over 10 years, fair value	14,038
Available for sale, amortized cost	41,498	38,760
Available for sale, fair value	41,527	38,846
Held to maturity, under 1 year, amortized cost	490
Held to maturity, under 1 year, fair value	473
Held to maturity, 1 to 5 years, amortized cost	4,183
Held to maturity, 1 to 5 years, fair value	3,805
Held to maturity, 6 to 10 years, amortized cost	967
Held to maturity, 6 to 10 years, fair value	893
Held to maturity, over 10 years, amortized cost	26,820
Held to maturity, over 10 years, fair value	23,176
Held to maturity, amortized cost	32,460	33,449
Investment securities held-to-maturity	28,347	29,490
Direct obligations
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	4,569
Available for sale, under 1 year, fair value	4,572
Available for sale, 1 to 5 years, amortized cost	20,412
Available for sale, 1 to 5 years, fair value	20,435
Available for sale, 6 to 10 years, amortized cost	1
Available for sale, 6 to 10 years, fair value	1
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	24,982	23,210
Available for sale, fair value	25,008	23,260
Held to maturity, under 1 year, amortized cost	243
Held to maturity, under 1 year, fair value	242
Held to maturity, 1 to 5 years, amortized cost	24
Held to maturity, 1 to 5 years, fair value	23
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	7
Held to maturity, over 10 years, fair value	7
Held to maturity, amortized cost	274	573
Investment securities held-to-maturity	272	570
Mortgage-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	67
Available for sale, under 1 year, fair value	67
Available for sale, 1 to 5 years, amortized cost	1,699
Available for sale, 1 to 5 years, fair value	1,692
Available for sale, 6 to 10 years, amortized cost	728
Available for sale, 6 to 10 years, fair value	722
Available for sale, over 10 years, amortized cost	14,022
Available for sale, over 10 years, fair value	14,038
Available for sale, amortized cost	16,516	15,550
Available for sale, fair value	16,519	15,586
Held to maturity, under 1 year, amortized cost	247
Held to maturity, under 1 year, fair value	231
Held to maturity, 1 to 5 years, amortized cost	4,159
Held to maturity, 1 to 5 years, fair value	3,782
Held to maturity, 6 to 10 years, amortized cost	967
Held to maturity, 6 to 10 years, fair value	893
Held to maturity, over 10 years, amortized cost	26,813
Held to maturity, over 10 years, fair value	23,169
Held to maturity, amortized cost	32,186	32,876
Investment securities held-to-maturity	28,075	28,920
Total non-U.S. debt securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	5,018
Available for sale, under 1 year, fair value	5,022
Available for sale, 1 to 5 years, amortized cost	17,712
Available for sale, 1 to 5 years, fair value	17,656
Available for sale, 6 to 10 years, amortized cost	1,472
Available for sale, 6 to 10 years, fair value	1,474
Available for sale, over 10 years, amortized cost	2,950
Available for sale, over 10 years, fair value	2,950
Available for sale, amortized cost	27,152	25,131
Available for sale, fair value	27,102	25,220
Held to maturity, under 1 year, amortized cost	772
Held to maturity, under 1 year, fair value	770
Held to maturity, 1 to 5 years, amortized cost	1,220
Held to maturity, 1 to 5 years, fair value	1,190
Held to maturity, 6 to 10 years, amortized cost	92
Held to maturity, 6 to 10 years, fair value	89
Held to maturity, over 10 years, amortized cost	0
Held to maturity, over 10 years, fair value	0
Held to maturity, amortized cost	2,084	2,461
Investment securities held-to-maturity	2,049	2,434
Mortgage-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	184
Available for sale, under 1 year, fair value	184
Available for sale, 1 to 5 years, amortized cost	418
Available for sale, 1 to 5 years, fair value	418
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	2,041
Available for sale, over 10 years, fair value	2,041
Available for sale, amortized cost	2,643	2,573
Available for sale, fair value	2,643	2,578
Asset-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	42
Available for sale, under 1 year, fair value	42
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	1,055
Available for sale, 6 to 10 years, fair value	1,058
Available for sale, over 10 years, amortized cost	909
Available for sale, over 10 years, fair value	909
Available for sale, amortized cost	2,290	2,081
Available for sale, fair value	2,293	2,085
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	3,897
Available for sale, under 1 year, fair value	3,898
Available for sale, 1 to 5 years, amortized cost	15,116
Available for sale, 1 to 5 years, fair value	15,043
Available for sale, 6 to 10 years, amortized cost	338
Available for sale, 6 to 10 years, fair value	338
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	19,351	17,693
Available for sale, fair value	19,279	17,731
Held to maturity, under 1 year, amortized cost	772
Held to maturity, under 1 year, fair value	770
Held to maturity, 1 to 5 years, amortized cost	1,220
Held to maturity, 1 to 5 years, fair value	1,190
Held to maturity, 6 to 10 years, amortized cost	92
Held to maturity, 6 to 10 years, fair value	89
Held to maturity, over 10 years, amortized cost	0
Held to maturity, over 10 years, fair value	0
Held to maturity, amortized cost	2,084	2,461
Investment securities held-to-maturity	2,049	2,434
Other
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	895
Available for sale, under 1 year, fair value	898
Available for sale, 1 to 5 years, amortized cost	1,894
Available for sale, 1 to 5 years, fair value	1,911
Available for sale, 6 to 10 years, amortized cost	79
Available for sale, 6 to 10 years, fair value	78
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	2,868	2,784
Available for sale, fair value	2,887	2,826
Total asset-backed securities
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	106
Available for sale, 1 to 5 years, amortized cost	97
Available for sale, 1 to 5 years, fair value	98
Available for sale, 6 to 10 years, amortized cost	1,301
Available for sale, 6 to 10 years, fair value	1,300
Available for sale, over 10 years, amortized cost	1,489
Available for sale, over 10 years, fair value	1,487
Available for sale, amortized cost	2,994	3,057
Available for sale, fair value	2,991	3,063
Held to maturity, under 1 year, amortized cost	121
Held to maturity, under 1 year, fair value	118
Held to maturity, 1 to 5 years, amortized cost	391
Held to maturity, 1 to 5 years, fair value	390
Held to maturity, 6 to 10 years, amortized cost	458
Held to maturity, 6 to 10 years, fair value	457
Held to maturity, over 10 years, amortized cost	1,218
Held to maturity, over 10 years, fair value	1,199
Held to maturity, amortized cost	2,188	2,261
Investment securities held-to-maturity	2,164	2,242
Student loans
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	37
Available for sale, over 10 years, fair value	37
Available for sale, amortized cost	37	63
Available for sale, fair value	37	64
Held to maturity, under 1 year, amortized cost	121
Held to maturity, under 1 year, fair value	118
Held to maturity, 1 to 5 years, amortized cost	391
Held to maturity, 1 to 5 years, fair value	390
Held to maturity, 6 to 10 years, amortized cost	458
Held to maturity, 6 to 10 years, fair value	457
Held to maturity, over 10 years, amortized cost	1,218
Held to maturity, over 10 years, fair value	1,199
Held to maturity, amortized cost	2,188	2,261
Investment securities held-to-maturity	2,164	2,242
Collateralized loan obligations
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	106
Available for sale, 1 to 5 years, amortized cost	7
Available for sale, 1 to 5 years, fair value	7
Available for sale, 6 to 10 years, amortized cost	1,301
Available for sale, 6 to 10 years, fair value	1,300
Available for sale, over 10 years, amortized cost	1,452
Available for sale, over 10 years, fair value	1,450
Available for sale, amortized cost	2,867	2,904
Available for sale, fair value	2,863	2,905
Non-agency CMBS and RMBS
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, amortized cost	0	0
Available for sale, fair value	0	3
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
State and political subdivisions
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	25
Available for sale, under 1 year, fair value	25
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	0
Available for sale, amortized cost	25	25
Available for sale, fair value	$ 25	25
Other
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, fair value		$ 0