Investment Securities - Schedule of Contractual Maturities of Debt Securities (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	$ 7,299
Available for sale, under 1 year, fair value	7,244
Available for sale, 1 to 5 years, amortized cost	17,579
Available for sale, 1 to 5 years, fair value	17,120
Available for sale, 6 to 10 years, amortized cost	10,178
Available for sale, 6 to 10 years, fair value	10,046
Available for sale, over 10 years, amortized cost	7,321
Available for sale, over 10 years, fair value	7,136
Available for sale, amortized cost	42,377	$ 41,858
Available for sale, fair value	41,546	40,579
Held to maturity, amortized cost	61,956	64,700
Investment securities held-to-maturity	54,121	57,913
Direct obligations
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	291
Available for sale, under 1 year, fair value	291
Available for sale, 1 to 5 years, amortized cost	6,920
Available for sale, 1 to 5 years, fair value	6,730
Available for sale, 6 to 10 years, amortized cost	601
Available for sale, 6 to 10 years, fair value	606
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	7,812	8,232
Available for sale, fair value	7,627	7,981
Held to maturity, under 1 year, amortized cost	6,284
Held to maturity, under 1 year, fair value	6,230
Held to maturity, 1 to 5 years, amortized cost	5,439
Held to maturity, 1 to 5 years, fair value	5,206
Held to maturity, 6 to 10 years, amortized cost	24
Held to maturity, 6 to 10 years, fair value	22
Held to maturity, over 10 years, amortized cost	11
Held to maturity, over 10 years, fair value	11
Held to maturity, amortized cost	11,758	11,693
Investment securities held-to-maturity	11,469	11,352
Mortgage-backed securities
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	1,309
Available for sale, 1 to 5 years, fair value	1,291
Available for sale, 6 to 10 years, amortized cost	4,398
Available for sale, 6 to 10 years, fair value	4,307
Available for sale, over 10 years, amortized cost	4,518
Available for sale, over 10 years, fair value	4,347
Available for sale, amortized cost	10,266	8,767
Available for sale, fair value	9,986	8,509
Held to maturity, under 1 year, amortized cost	132
Held to maturity, under 1 year, fair value	115
Held to maturity, 1 to 5 years, amortized cost	594
Held to maturity, 1 to 5 years, fair value	547
Held to maturity, 6 to 10 years, amortized cost	4,523
Held to maturity, 6 to 10 years, fair value	3,653
Held to maturity, over 10 years, amortized cost	35,048
Held to maturity, over 10 years, fair value	28,750
Held to maturity, amortized cost	40,297	42,307
Investment securities held-to-maturity	33,065	36,280
Total U.S. Treasury and federal agencies
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	332
Available for sale, 1 to 5 years, amortized cost	8,229
Available for sale, 1 to 5 years, fair value	8,021
Available for sale, 6 to 10 years, amortized cost	4,999
Available for sale, 6 to 10 years, fair value	4,913
Available for sale, over 10 years, amortized cost	4,518
Available for sale, over 10 years, fair value	4,347
Available for sale, amortized cost	18,078	16,999
Available for sale, fair value	17,613	16,490
Held to maturity, under 1 year, amortized cost	6,416
Held to maturity, under 1 year, fair value	6,345
Held to maturity, 1 to 5 years, amortized cost	6,033
Held to maturity, 1 to 5 years, fair value	5,753
Held to maturity, 6 to 10 years, amortized cost	4,547
Held to maturity, 6 to 10 years, fair value	3,675
Held to maturity, over 10 years, amortized cost	35,059
Held to maturity, over 10 years, fair value	28,761
Held to maturity, amortized cost	52,055	54,000
Investment securities held-to-maturity	44,534	47,632
Mortgage-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	142
Available for sale, under 1 year, fair value	142
Available for sale, 1 to 5 years, amortized cost	243
Available for sale, 1 to 5 years, fair value	242
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	1,166
Available for sale, over 10 years, fair value	1,157
Available for sale, amortized cost	1,551	1,642
Available for sale, fair value	1,541	1,623
Asset-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	319
Available for sale, under 1 year, fair value	315
Available for sale, 1 to 5 years, amortized cost	419
Available for sale, 1 to 5 years, fair value	415
Available for sale, 6 to 10 years, amortized cost	554
Available for sale, 6 to 10 years, fair value	551
Available for sale, over 10 years, amortized cost	611
Available for sale, over 10 years, fair value	609
Available for sale, amortized cost	1,903	1,696
Available for sale, fair value	1,890	1,669
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	5,627
Available for sale, under 1 year, fair value	5,591
Available for sale, 1 to 5 years, amortized cost	6,483
Available for sale, 1 to 5 years, fair value	6,304
Available for sale, 6 to 10 years, amortized cost	2,800
Available for sale, 6 to 10 years, fair value	2,771
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	14,910	14,512
Available for sale, fair value	14,666	14,089
Held to maturity, under 1 year, amortized cost	2,261
Held to maturity, under 1 year, fair value	2,231
Held to maturity, 1 to 5 years, amortized cost	3,690
Held to maturity, 1 to 5 years, fair value	3,504
Held to maturity, 6 to 10 years, amortized cost	501
Held to maturity, 6 to 10 years, fair value	455
Held to maturity, over 10 years, amortized cost	0
Held to maturity, over 10 years, fair value	0
Held to maturity, amortized cost	6,452	6,603
Investment securities held-to-maturity	6,190	6,299
Other
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	341
Available for sale, under 1 year, fair value	335
Available for sale, 1 to 5 years, amortized cost	1,570
Available for sale, 1 to 5 years, fair value	1,515
Available for sale, 6 to 10 years, amortized cost	174
Available for sale, 6 to 10 years, fair value	172
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	2,085	2,255
Available for sale, fair value	2,022	2,091
Total non-U.S. debt securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	6,429
Available for sale, under 1 year, fair value	6,383
Available for sale, 1 to 5 years, amortized cost	8,715
Available for sale, 1 to 5 years, fair value	8,476
Available for sale, 6 to 10 years, amortized cost	3,528
Available for sale, 6 to 10 years, fair value	3,494
Available for sale, over 10 years, amortized cost	1,777
Available for sale, over 10 years, fair value	1,766
Available for sale, amortized cost	20,449	20,105
Available for sale, fair value	20,119	19,472
Held to maturity, under 1 year, amortized cost	2,261
Held to maturity, under 1 year, fair value	2,231
Held to maturity, 1 to 5 years, amortized cost	3,690
Held to maturity, 1 to 5 years, fair value	3,504
Held to maturity, 6 to 10 years, amortized cost	501
Held to maturity, 6 to 10 years, fair value	455
Held to maturity, over 10 years, amortized cost	0
Held to maturity, over 10 years, fair value	0
Held to maturity, amortized cost	6,452	6,603
Investment securities held-to-maturity	6,190	6,299
Student loans
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	33
Available for sale, under 1 year, fair value	33
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	85
Available for sale, over 10 years, fair value	85
Available for sale, amortized cost	118	116
Available for sale, fair value	118	115
Held to maturity, under 1 year, amortized cost	237
Held to maturity, under 1 year, fair value	231
Held to maturity, 1 to 5 years, amortized cost	232
Held to maturity, 1 to 5 years, fair value	231
Held to maturity, 6 to 10 years, amortized cost	622
Held to maturity, 6 to 10 years, fair value	612
Held to maturity, over 10 years, amortized cost	2,351
Held to maturity, over 10 years, fair value	2,298
Held to maturity, amortized cost	3,442	3,955
Investment securities held-to-maturity	3,372	3,822
Collateralized loan obligations
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	345
Available for sale, 1 to 5 years, fair value	343
Available for sale, 6 to 10 years, amortized cost	1,489
Available for sale, 6 to 10 years, fair value	1,482
Available for sale, over 10 years, amortized cost	693
Available for sale, over 10 years, fair value	693
Available for sale, amortized cost	2,649	2,394
Available for sale, fair value	2,640	2,355
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	20
Available for sale, 1 to 5 years, fair value	19
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	248
Available for sale, over 10 years, fair value	245
Available for sale, amortized cost	268	237
Available for sale, fair value	264	231
Held to maturity, under 1 year, amortized cost	1
Held to maturity, under 1 year, fair value	8
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	6
Held to maturity, over 10 years, fair value	17
Held to maturity, amortized cost	7	142
Investment securities held-to-maturity	25	160
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	90
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	90	88
Total asset-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	155
Available for sale, under 1 year, fair value	155
Available for sale, 1 to 5 years, amortized cost	455
Available for sale, 1 to 5 years, fair value	452
Available for sale, 6 to 10 years, amortized cost	1,489
Available for sale, 6 to 10 years, fair value	1,482
Available for sale, over 10 years, amortized cost	1,026
Available for sale, over 10 years, fair value	1,023
Available for sale, amortized cost	3,125	2,837
Available for sale, fair value	3,112	2,789
Held to maturity, under 1 year, amortized cost	238
Held to maturity, under 1 year, fair value	239
Held to maturity, 1 to 5 years, amortized cost	232
Held to maturity, 1 to 5 years, fair value	231
Held to maturity, 6 to 10 years, amortized cost	622
Held to maturity, 6 to 10 years, fair value	612
Held to maturity, over 10 years, amortized cost	2,357
Held to maturity, over 10 years, fair value	2,315
Held to maturity, amortized cost	3,449	4,097
Investment securities held-to-maturity	3,397	3,982
State and political subdivisions
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	125
Available for sale, under 1 year, fair value	122
Available for sale, 1 to 5 years, amortized cost	100
Available for sale, 1 to 5 years, fair value	98
Available for sale, 6 to 10 years, amortized cost	162
Available for sale, 6 to 10 years, fair value	157
Available for sale, over 10 years, amortized cost	0
Available for sale, over 10 years, fair value	0
Available for sale, amortized cost	387	839
Available for sale, fair value	377	823
Other U.S. debt securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, under 1 year, amortized cost	258
Available for sale, under 1 year, fair value	252
Available for sale, 1 to 5 years, amortized cost	80
Available for sale, 1 to 5 years, fair value	73
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	338	1,078
Available for sale, fair value	325	$ 1,005
Total
Contractual Maturities Of Debt Investment Securities [Line Items]
Held to maturity, under 1 year, amortized cost	8,915
Held to maturity, under 1 year, fair value	8,815
Held to maturity, 1 to 5 years, amortized cost	9,955
Held to maturity, 1 to 5 years, fair value	9,488
Held to maturity, 6 to 10 years, amortized cost	5,670
Held to maturity, 6 to 10 years, fair value	4,742
Held to maturity, over 10 years, amortized cost	37,416
Held to maturity, over 10 years, fair value	31,076
Held to maturity, amortized cost	61,956
Investment securities held-to-maturity	$ 54,121