FAIR VALUE MEASUREMENT - Level 3 Roll Forward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Gains (losses), location		Realized gains on sales of investments, net
Trading account assets and liabilities
Fair value, Derivative assets (liabilities) measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset (liability), net	$ (2,218)	$ (578)
Net realized/unrealized gains (losses) included in principal transactions	408	(1,744)
Net realized/unrealized gains (losses) included in locations Other	0	0
Transfers into Level 3	266	185
Transfers out of Level 3	818	974
Purchases	(955)	(1,060)
Issuances	19	6
Sales	(375)	(197)
Settlements	712	196
Balance at end of period, asset (liability), net	(1,325)	(2,218)
Unrealized gains (losses) still held	(721)	(2,890)
Trading account assets and liabilities | Interest rate contracts
Fair value, Derivative assets (liabilities) measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset (liability), net	(1,085)	355
Net realized/unrealized gains (losses) included in principal transactions	(875)	(1,588)
Net realized/unrealized gains (losses) included in locations Other	0	0
Transfers into Level 3	275	(172)
Transfers out of Level 3	462	(314)
Purchases	94	21
Issuances	19	6
Sales	(35)	58
Settlements	815	549
Balance at end of period, asset (liability), net	(330)	(1,085)
Unrealized gains (losses) still held	(381)	(1,481)
Trading account assets and liabilities | Foreign exchange contracts
Fair value, Derivative assets (liabilities) measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset (liability), net	295	50
Net realized/unrealized gains (losses) included in principal transactions	600	412
Net realized/unrealized gains (losses) included in locations Other	0	0
Transfers into Level 3	100	91
Transfers out of Level 3	(485)	46
Purchases	13	135
Issuances	0	0
Sales	(197)	(107)
Settlements	(141)	(332)
Balance at end of period, asset (liability), net	185	295
Unrealized gains (losses) still held	(474)	(144)
Trading account assets and liabilities | Equity contracts
Fair value, Derivative assets (liabilities) measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset (liability), net	(1,634)	(1,104)
Net realized/unrealized gains (losses) included in principal transactions	68	(672)
Net realized/unrealized gains (losses) included in locations Other	0	0
Transfers into Level 3	(135)	32
Transfers out of Level 3	1,022	858
Purchases	(954)	(819)
Issuances	0	0
Sales	(77)	(114)
Settlements	22	185
Balance at end of period, asset (liability), net	(1,688)	(1,634)
Unrealized gains (losses) still held	(459)	(927)
Trading account assets and liabilities | Commodity contracts
Fair value, Derivative assets (liabilities) measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset (liability), net	279	278
Net realized/unrealized gains (losses) included in principal transactions	460	324
Net realized/unrealized gains (losses) included in locations Other	0	0
Transfers into Level 3	46	235
Transfers out of Level 3	(210)	77
Purchases	(104)	(389)
Issuances	0	0
Sales	(66)	(34)
Settlements	(1)	(212)
Balance at end of period, asset (liability), net	404	279
Unrealized gains (losses) still held	512	(284)
Trading account assets and liabilities | Credit derivatives
Fair value, Derivative assets (liabilities) measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset (liability), net	(73)	(157)
Net realized/unrealized gains (losses) included in principal transactions	155	(220)
Net realized/unrealized gains (losses) included in locations Other	0	0
Transfers into Level 3	(20)	(1)
Transfers out of Level 3	29	307
Purchases	(4)	(8)
Issuances	0	0
Sales	0	0
Settlements	17	6
Balance at end of period, asset (liability), net	104	(73)
Unrealized gains (losses) still held	81	(54)
Deposits
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	29	15
Net realized/unrealized gains (losses) included in principal transactions	1	(7)
Net realized/unrealized gains (losses) included in locations Other	4	(4)
Transfers into Level 3	51	50
Transfers out of Level 3	(40)	(118)
Purchases	0	0
Issuances	39	84
Sales	0	0
Settlements	(35)	(13)
Balance at end of period	39	29
Unrealized gains (losses) still held	1	9
Securities loaned and sold under agreements to repurchase
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	390	1,031
Net realized/unrealized gains (losses) included in principal transactions	5	(5)
Net realized/unrealized gains (losses) included in locations Other	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	(24)
Purchases	976	1,335
Issuances	0	61
Sales	0	0
Settlements	(971)	(2,018)
Balance at end of period	390	390
Unrealized gains (losses) still held	5	0
Trading account liabilities | Securities sold, not yet purchased
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	35	50
Net realized/unrealized gains (losses) included in principal transactions	(14)	(30)
Net realized/unrealized gains (losses) included in locations Other	0	0
Transfers into Level 3	35	22
Transfers out of Level 3	(30)	(49)
Purchases	116	123
Issuances	0	0
Sales	0	0
Settlements	(142)	(141)
Balance at end of period	28	35
Unrealized gains (losses) still held	5	(13)
Trading account liabilities | Other trading liabilities
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	0	3
Net realized/unrealized gains (losses) included in principal transactions	0	1
Net realized/unrealized gains (losses) included in locations Other	0	0
Transfers into Level 3	0	4
Transfers out of Level 3	0	(2)
Purchases	0	3
Issuances	0	0
Sales	0	0
Settlements	0	(7)
Balance at end of period	0	0
Unrealized gains (losses) still held	0	0
Short-term borrowings
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	481	38
Net realized/unrealized gains (losses) included in principal transactions	(94)	44
Net realized/unrealized gains (losses) included in locations Other	0	0
Transfers into Level 3	88	62
Transfers out of Level 3	(560)	(31)
Purchases	1	2
Issuances	479	488
Sales	0	0
Settlements	(286)	(34)
Balance at end of period	297	481
Unrealized gains (losses) still held	(37)	(27)
Long-term debt
Fair value, Derivative assets (liabilities) measured on recurring basis, level 3 fair-value category reconciliation
Transfers into Level 3	4,600	4,900
Transfers out of Level 3	(22,900)	(10,200)
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	38,380	36,117
Net realized/unrealized gains (losses) included in principal transactions	1,757	(1,039)
Net realized/unrealized gains (losses) included in locations Other	0	0
Transfers into Level 3	4,626	4,913
Transfers out of Level 3	(22,923)	(10,215)
Purchases	0	0
Issuances	5,995	9,811
Sales	0	0
Settlements	(3,221)	(3,285)
Balance at end of period	21,100	38,380
Unrealized gains (losses) still held	1,731	(2,644)
Other financial liabilities measured on a recurring basis
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	6	2
Net realized/unrealized gains (losses) included in principal transactions	0	0
Net realized/unrealized gains (losses) included in locations Other	0	6
Transfers into Level 3	0	0
Transfers out of Level 3	0	(1)
Purchases	0	6
Issuances	5	49
Sales	0	(20)
Settlements	(11)	(24)
Balance at end of period	0	6
Unrealized gains (losses) still held	0	0
Securities borrowed and purchased under agreements to resell
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	139	149
Net realized/unrealized gains (losses) included in principal transactions	(4)	8
Net realized/unrealized gains (losses) included in Other	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	(2)
Purchases	111	308
Issuances	0	0
Sales	0	0
Settlements	(118)	(324)
Balance at end of period	128	139
Unrealized gains (losses) still held	(4)	13
Trading non-derivative assets
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	3,119	2,940
Net realized/unrealized gains (losses) included in principal transactions	237	525
Net realized/unrealized gains (losses) included in Other	0	0
Transfers into Level 3	1,319	1,838
Transfers out of Level 3	(2,393)	(2,114)
Purchases	2,586	4,134
Issuances	34	2
Sales	(3,491)	(4,200)
Settlements	(34)	(6)
Balance at end of period	1,377	3,119
Unrealized gains (losses) still held	88	74
Trading non-derivative assets | U.S. government-sponsored agency guaranteed
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	581	600
Net realized/unrealized gains (losses) included in principal transactions	(50)	7
Net realized/unrealized gains (losses) included in Other	0	0
Transfers into Level 3	456	396
Transfers out of Level 3	(856)	(543)
Purchases	667	616
Issuances	0	0
Sales	(497)	(495)
Settlements	0	0
Balance at end of period	301	581
Unrealized gains (losses) still held	(18)	14
Trading non-derivative assets | Residential
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	116	166
Net realized/unrealized gains (losses) included in principal transactions	(8)	2
Net realized/unrealized gains (losses) included in Other	0	0
Transfers into Level 3	84	103
Transfers out of Level 3	(79)	(110)
Purchases	159	197
Issuances	0	0
Sales	(205)	(242)
Settlements	0	0
Balance at end of period	67	116
Unrealized gains (losses) still held	(1)	(20)
Trading non-derivative assets | Commercial
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	202	145
Net realized/unrealized gains (losses) included in principal transactions	17	(25)
Net realized/unrealized gains (losses) included in Other	0	0
Transfers into Level 3	56	202
Transfers out of Level 3	(189)	(88)
Purchases	162	118
Issuances	0	0
Sales	(212)	(150)
Settlements	0	0
Balance at end of period	36	202
Unrealized gains (losses) still held	(4)	(15)
Trading non-derivative assets | Mortgage-backed securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	899	911
Net realized/unrealized gains (losses) included in principal transactions	(41)	(16)
Net realized/unrealized gains (losses) included in Other	0	0
Transfers into Level 3	596	701
Transfers out of Level 3	(1,124)	(741)
Purchases	988	931
Issuances	0	0
Sales	(914)	(887)
Settlements	0	0
Balance at end of period	404	899
Unrealized gains (losses) still held	(23)	(21)
Trading non-derivative assets | U.S. Treasury and federal agency securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	7	1
Net realized/unrealized gains (losses) included in principal transactions	4	(4)
Net realized/unrealized gains (losses) included in Other	0	0
Transfers into Level 3	1	10
Transfers out of Level 3	(1)	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	(10)	0
Balance at end of period	1	7
Unrealized gains (losses) still held	0	0
Trading non-derivative assets | State and municipal
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	3	7
Net realized/unrealized gains (losses) included in principal transactions	2	(3)
Net realized/unrealized gains (losses) included in Other	0	0
Transfers into Level 3	20	21
Transfers out of Level 3	(10)	(2)
Purchases	0	0
Issuances	0	0
Sales	(4)	(20)
Settlements	0	0
Balance at end of period	11	3
Unrealized gains (losses) still held	1	0
Trading non-derivative assets | Foreign government
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	54	119
Net realized/unrealized gains (losses) included in principal transactions	(9)	(18)
Net realized/unrealized gains (losses) included in Other	0	0
Transfers into Level 3	21	8
Transfers out of Level 3	(49)	(66)
Purchases	192	174
Issuances	0	0
Sales	(194)	(163)
Settlements	0	0
Balance at end of period	15	54
Unrealized gains (losses) still held	0	(1)
Trading non-derivative assets | Corporate
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	500	394
Net realized/unrealized gains (losses) included in principal transactions	155	289
Net realized/unrealized gains (losses) included in Other	0	0
Transfers into Level 3	188	285
Transfers out of Level 3	(484)	(691)
Purchases	587	1,163
Issuances	0	0
Sales	(669)	(940)
Settlements	(8)	0
Balance at end of period	269	500
Unrealized gains (losses) still held	97	(6)
Trading non-derivative assets | Marketable equity securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	292	192
Net realized/unrealized gains (losses) included in principal transactions	5	68
Net realized/unrealized gains (losses) included in Other	0	0
Transfers into Level 3	239	99
Transfers out of Level 3	(75)	(39)
Purchases	169	146
Issuances	0	0
Sales	(464)	(174)
Settlements	0	0
Balance at end of period	166	292
Unrealized gains (losses) still held	(8)	62
Trading non-derivative assets | Asset-backed securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	531	668
Net realized/unrealized gains (losses) included in principal transactions	(53)	25
Net realized/unrealized gains (losses) included in Other	0	0
Transfers into Level 3	54	105
Transfers out of Level 3	(210)	(138)
Purchases	273	801
Issuances	0	0
Sales	(417)	(930)
Settlements	0	0
Balance at end of period	178	531
Unrealized gains (losses) still held	(21)	12
Trading non-derivative assets | Other trading assets
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	833	648
Net realized/unrealized gains (losses) included in principal transactions	174	184
Net realized/unrealized gains (losses) included in Other	0	0
Transfers into Level 3	200	609
Transfers out of Level 3	(440)	(437)
Purchases	377	919
Issuances	34	2
Sales	(829)	(1,086)
Settlements	(16)	(6)
Balance at end of period	333	833
Unrealized gains (losses) still held	42	28
Investments
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	1,799	2,049
Net realized/unrealized gains (losses) included in principal transactions	0	0
Net realized/unrealized gains (losses) included in Other	(86)	64
Transfers into Level 3	96	116
Transfers out of Level 3	(620)	(560)
Purchases	436	1,337
Issuances	0	0
Sales	(549)	(1,207)
Settlements	0	0
Balance at end of period	1,076	1,799
Unrealized gains (losses) still held	(29)	109
Investments | U.S. government-sponsored agency guaranteed
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	75	30
Net realized/unrealized gains (losses) included in principal transactions	0	0
Net realized/unrealized gains (losses) included in Other	4	4
Transfers into Level 3	3	0
Transfers out of Level 3	0	(3)
Purchases	7	47
Issuances	0	0
Sales	(53)	(3)
Settlements	0	0
Balance at end of period	36	75
Unrealized gains (losses) still held	5	2
Investments | Residential
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	116	41
Net realized/unrealized gains (losses) included in principal transactions	0	0
Net realized/unrealized gains (losses) included in Other	(3)	1
Transfers into Level 3	5	0
Transfers out of Level 3	(90)	0
Purchases	0	90
Issuances	0	0
Sales	0	(16)
Settlements	0	0
Balance at end of period	28	116
Unrealized gains (losses) still held	(3)	1
Investments | Commercial
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	0	0
Net realized/unrealized gains (losses) included in principal transactions	0	0
Net realized/unrealized gains (losses) included in Other	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	0	0
Balance at end of period	0	0
Unrealized gains (losses) still held	0	0
Investments | Mortgage-backed securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	191	71
Net realized/unrealized gains (losses) included in principal transactions	0	0
Net realized/unrealized gains (losses) included in Other	1	5
Transfers into Level 3	8	0
Transfers out of Level 3	(90)	(3)
Purchases	7	137
Issuances	0	0
Sales	(53)	(19)
Settlements	0	0
Balance at end of period	64	191
Unrealized gains (losses) still held	2	3
Investments | U.S. Treasury and federal agency securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	0	0
Net realized/unrealized gains (losses) included in principal transactions	0	0
Net realized/unrealized gains (losses) included in Other	0	(1)
Transfers into Level 3	0	0
Transfers out of Level 3	0	(20)
Purchases	0	51
Issuances	0	0
Sales	0	(30)
Settlements	0	0
Balance at end of period	0	0
Unrealized gains (losses) still held	0	0
Investments | State and municipal
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	542	586
Net realized/unrealized gains (losses) included in principal transactions	0	0
Net realized/unrealized gains (losses) included in Other	(31)	27
Transfers into Level 3	0	2
Transfers out of Level 3	(8)	(86)
Purchases	14	64
Issuances	0	0
Sales	(89)	(51)
Settlements	0	0
Balance at end of period	428	542
Unrealized gains (losses) still held	(14)	31
Investments | Foreign government
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	194	608
Net realized/unrealized gains (losses) included in principal transactions	0	0
Net realized/unrealized gains (losses) included in Other	(16)	(13)
Transfers into Level 3	8	27
Transfers out of Level 3	(174)	(327)
Purchases	36	850
Issuances	0	0
Sales	(36)	(951)
Settlements	0	0
Balance at end of period	12	194
Unrealized gains (losses) still held	(3)	(3)
Investments | Corporate
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	362	343
Net realized/unrealized gains (losses) included in principal transactions	0	0
Net realized/unrealized gains (losses) included in Other	(24)	(2)
Transfers into Level 3	78	49
Transfers out of Level 3	(348)	(61)
Purchases	183	131
Issuances	0	0
Sales	(105)	(98)
Settlements	0	0
Balance at end of period	146	362
Unrealized gains (losses) still held	(7)	(4)
Investments | Marketable equity securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	27	10
Net realized/unrealized gains (losses) included in principal transactions	0	0
Net realized/unrealized gains (losses) included in Other	(13)	17
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	0	0
Balance at end of period	14	27
Unrealized gains (losses) still held	0	0
Investments | Asset-backed securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	0	1
Net realized/unrealized gains (losses) included in principal transactions	0	0
Net realized/unrealized gains (losses) included in Other	0	(1)
Transfers into Level 3	2	30
Transfers out of Level 3	0	0
Purchases	3	0
Issuances	0	0
Sales	(3)	(30)
Settlements	0	0
Balance at end of period	2	0
Unrealized gains (losses) still held	0	0
Investments | Other debt securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	0	0
Net realized/unrealized gains (losses) included in principal transactions	0	0
Net realized/unrealized gains (losses) included in Other	0	1
Transfers into Level 3	0	0
Transfers out of Level 3	0	(63)
Purchases	6	62
Issuances	0	0
Sales	0	0
Settlements	0	0
Balance at end of period	6	0
Unrealized gains (losses) still held	0	0
Investments | Non-marketable equity securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	483	430
Net realized/unrealized gains (losses) included in principal transactions	0	0
Net realized/unrealized gains (losses) included in Other	(3)	31
Transfers into Level 3	0	8
Transfers out of Level 3	0	0
Purchases	187	42
Issuances	0	0
Sales	(263)	(28)
Settlements	0	0
Balance at end of period	404	483
Unrealized gains (losses) still held	(7)	82
Loans
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	427	1,361
Net realized/unrealized gains (losses) included in principal transactions	0	0
Net realized/unrealized gains (losses) included in Other	(85)	(236)
Transfers into Level 3	664	32
Transfers out of Level 3	(896)	(309)
Purchases	0	0
Issuances	250	241
Sales	0	0
Settlements	(98)	(662)
Balance at end of period	262	427
Unrealized gains (losses) still held	(6)	(16)
Mortgage servicing rights
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	691	665
Net realized/unrealized gains (losses) included in principal transactions	0	0
Net realized/unrealized gains (losses) included in Other	37	28
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases	0	0
Issuances	104	66
Sales	0	0
Settlements	(72)	(68)
Balance at end of period	760	691
Unrealized gains (losses) still held	44	20
Other financial assets
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period	30	57
Net realized/unrealized gains (losses) included in principal transactions	0	0
Net realized/unrealized gains (losses) included in Other	(1)	(24)
Transfers into Level 3	0	0
Transfers out of Level 3	0	(2)
Purchases	5	50
Issuances	51	22
Sales	(5)	(32)
Settlements	(65)	(41)
Balance at end of period	15	30
Unrealized gains (losses) still held	$ (1)	$ 0