Investment Securities - Schedule of Gross Pre-Tax Unrealized Losses on Investment Securities (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	$ 13,203	$ 19,429
Available for sale, gross unrealized losses less than 12 months	203	369
Available for sale, fair value 12 months or longer	24,415	18,093
Available for sale, gross unrealized losses 12 months or longer	647	924
Available for sale, fair value total	37,618	37,522
Available for sale, gross unrealized losses total	850	1,293
Direct obligations
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	1,310	1,337
Available for sale, gross unrealized losses less than 12 months	27	15
Available for sale, fair value 12 months or longer	5,276	5,745
Available for sale, gross unrealized losses 12 months or longer	170	246
Available for sale, fair value total	6,586	7,082
Available for sale, gross unrealized losses total	197	261
Mortgage-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	3,202	5,524
Available for sale, gross unrealized losses less than 12 months	85	130
Available for sale, fair value 12 months or longer	6,717	2,815
Available for sale, gross unrealized losses 12 months or longer	195	130
Available for sale, fair value total	9,919	8,339
Available for sale, gross unrealized losses total	280	260
Total U.S. Treasury and federal agencies
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	4,512	6,861
Available for sale, gross unrealized losses less than 12 months	112	145
Available for sale, fair value 12 months or longer	11,993	8,560
Available for sale, gross unrealized losses 12 months or longer	365	376
Available for sale, fair value total	16,505	15,421
Available for sale, gross unrealized losses total	477	521
Mortgage-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	214	1,278
Available for sale, gross unrealized losses less than 12 months	1	15
Available for sale, fair value 12 months or longer	823	272
Available for sale, gross unrealized losses 12 months or longer	10	4
Available for sale, fair value total	1,037	1,550
Available for sale, gross unrealized losses total	11	19
Asset-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	225	859
Available for sale, gross unrealized losses less than 12 months	0	11
Available for sale, fair value 12 months or longer	1,124	765
Available for sale, gross unrealized losses 12 months or longer	14	16
Available for sale, fair value total	1,349	1,624
Available for sale, gross unrealized losses total	14	27
Non-U.S. sovereign, supranational and non-U.S. agency
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	6,715	6,750
Available for sale, gross unrealized losses less than 12 months	72	108
Available for sale, fair value 12 months or longer	7,077	5,800
Available for sale, gross unrealized losses 12 months or longer	174	316
Available for sale, fair value total	13,792	12,550
Available for sale, gross unrealized losses total	246	424
Other
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	855	771
Available for sale, gross unrealized losses less than 12 months	10	27
Available for sale, fair value 12 months or longer	902	1,233
Available for sale, gross unrealized losses 12 months or longer	54	137
Available for sale, fair value total	1,757	2,004
Available for sale, gross unrealized losses total	64	164
Total non-U.S. debt securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	8,009	9,658
Available for sale, gross unrealized losses less than 12 months	83	161
Available for sale, fair value 12 months or longer	9,926	8,070
Available for sale, gross unrealized losses 12 months or longer	252	473
Available for sale, fair value total	17,935	17,728
Available for sale, gross unrealized losses total	335	634
Student loans
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	68	89
Available for sale, gross unrealized losses less than 12 months	0	1
Available for sale, fair value 12 months or longer	0	0
Available for sale, gross unrealized losses 12 months or longer	0	0
Available for sale, fair value total	68	89
Available for sale, gross unrealized losses total	0	1
Collateralized loan obligations
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	328	1,577
Available for sale, gross unrealized losses less than 12 months	0	27
Available for sale, fair value 12 months or longer	1,860	710
Available for sale, gross unrealized losses 12 months or longer	11	12
Available for sale, fair value total	2,188	2,287
Available for sale, gross unrealized losses total	11	39
Non-agency CMBS and RMBS
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	39	193
Available for sale, gross unrealized losses less than 12 months	1	6
Available for sale, fair value 12 months or longer	180	3
Available for sale, gross unrealized losses 12 months or longer	3	0
Available for sale, fair value total	219	196
Available for sale, gross unrealized losses total	4	6
Other
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months		88
Available for sale, gross unrealized losses less than 12 months		2
Available for sale, fair value 12 months or longer		0
Available for sale, gross unrealized losses 12 months or longer		0
Available for sale, fair value total		88
Available for sale, gross unrealized losses total		2
Total asset-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	435	1,947
Available for sale, gross unrealized losses less than 12 months	1	36
Available for sale, fair value 12 months or longer	2,040	713
Available for sale, gross unrealized losses 12 months or longer	14	12
Available for sale, fair value total	2,475	2,660
Available for sale, gross unrealized losses total	15	48
State and political subdivisions
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	244	669
Available for sale, gross unrealized losses less than 12 months	7	12
Available for sale, fair value 12 months or longer	133	42
Available for sale, gross unrealized losses 12 months or longer	3	5
Available for sale, fair value total	377	711
Available for sale, gross unrealized losses total	10	17
Other U.S. debt securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	3	294
Available for sale, gross unrealized losses less than 12 months	0	15
Available for sale, fair value 12 months or longer	323	708
Available for sale, gross unrealized losses 12 months or longer	13	58
Available for sale, fair value total	326	1,002
Available for sale, gross unrealized losses total	$ 13	$ 73