FAIR VALUE MEASUREMENT - Items Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Assets, Fair Value Disclosure [Abstract]
Federal funds sold and securities borrowed and purchased under agreements to resell, Netting	$ (136,181)	$ (112,391)
Trading account assets	383,906	334,114
Netting agreements	(292,519)	(346,545)
Netting of cash collateral received	(15,376)	(23,136)
Trading derivatives	66,079	75,306
Investments	512,578	526,582
Loans held at fair value	5,134	5,360
Liabilities, Fair Value Disclosure [Abstract]
Federal funds purchased and securities loaned and sold under agreements to repurchase, Netting	(136,181)	(112,391)
Netting agreements	(292,519)	(346,545)
Netting of cash collateral paid	(23,990)	(30,032)
Total derivative liabilities	53,455	59,916
Fair Value Measured at Net Asset Value Per Share [Member]
Liabilities, Fair Value Disclosure [Abstract]
Investments measured at net asset value excluded from Level 3	29	27
Recurring
Assets, Fair Value Disclosure [Abstract]
Federal funds sold and securities borrowed and purchased under agreements to resell	391,367	350,294
Federal funds sold and securities borrowed and purchased under agreements to resell, Netting	(135,404)	(110,767)
Federal funds sold and securities borrowed and purchased under agreements to resell	255,963	239,527
Investments	241,345	250,547
Loans held at fair value	5,134	5,360
Mortgage servicing rights	658	665
Assets before netting	1,342,152	1,321,319
Netting, Assets, total of netting agreements and cash collateral received	(443,299)	(480,448)
Total assets	898,853	840,871
Liabilities, Fair Value Disclosure [Abstract]
Interest-bearing deposits	2,943	1,875
Federal funds purchased and securities loaned and sold under agreements to repurchase, Gross	175,756	156,853
Federal funds purchased and securities loaned and sold under agreements to repurchase, Netting	(109,524)	(85,967)
Federal funds purchased and securities loaned and sold under agreements to repurchase	66,232	70,886
Securities sold, not yet purchased	131,537	110,720
Trading liabilities	131,555	110,731
Short-term borrowings	6,873	6,222
Long-term debt	115,168	105,995
Total liabilities, Gross	807,142	822,608
Total liabilities, Netting	(426,033)	(462,544)
Total liabilities	381,109	360,064
Recurring | Trading account liabilities
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	369,964	436,493
Total trading derivatives and cash collateral, liability	369,964	436,493
Netting agreements	(292,519)	(346,545)
Netting of cash collateral paid	(23,990)	(30,032)
Netting, Liabilities, total of netting agreements and cash collateral received	(316,509)	(376,577)
Total derivative liabilities	53,455	59,916
Recurring | Trading account liabilities | Interest rate contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	163,043	172,620
Recurring | Trading account liabilities | Foreign exchange contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	128,732	185,995
Recurring | Trading account liabilities | Equity contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	44,599	43,783
Recurring | Trading account liabilities | Commodity contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	23,575	26,318
Recurring | Trading account liabilities | Credit derivatives
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	10,015	7,777
Recurring | Other financial liabilities measured on a recurring basis
Liabilities, Fair Value Disclosure [Abstract]
Netting of cash collateral paid		0
Netting, Liabilities, total of netting agreements and cash collateral received	0
Non-trading derivatives and other financial liabilities measured on a recurring basis, gross	4,883	4,439
Total other assets and cash collateral, gross	4,883	4,439
Recurring | Other trading liabilities
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	18	11
Recurring | Mortgage-backed securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	49,557	38,409
Investments	14,958	11,749
Recurring | Mortgage securitizations - U.S. agency-sponsored
Assets, Fair Value Disclosure [Abstract]
Trading account assets	46,062	35,478
Investments	14,616	11,262
Recurring | Residential
Assets, Fair Value Disclosure [Abstract]
Trading account assets	2,605	1,988
Investments	340	485
Recurring | Commercial
Assets, Fair Value Disclosure [Abstract]
Trading account assets	890	943
Investments	2	2
Recurring | U.S. Treasury and federal agency securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	99,801	67,581
Investments	86,677	92,290
Recurring | State and municipal
Assets, Fair Value Disclosure [Abstract]
Trading account assets	1,874	2,263
Investments	2,293	2,223
Recurring | Foreign government
Assets, Fair Value Disclosure [Abstract]
Trading account assets	82,338	64,352
Investments	125,084	133,277
Recurring | Corporate
Assets, Fair Value Disclosure [Abstract]
Trading account assets	16,109	13,942
Investments	5,251	4,916
Recurring | Equity securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	50,587	54,361
Investments	443	429
Recurring | Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	2,432	2,265
Investments	1,065	1,030
Recurring | Other trading assets
Assets, Fair Value Disclosure [Abstract]
Trading account assets	15,129	15,635
Investments	5,159	4,194
Recurring | Non-marketable equity securities
Assets, Fair Value Disclosure [Abstract]
Investments	415	439
Recurring | Trading non-derivative assets
Assets, Fair Value Disclosure [Abstract]
Trading account assets	317,827	258,808
Recurring | Trading account derivatives
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	373,974	444,987
Trading derivative, asset, gross net cash collateral paid	373,974	444,987
Netting agreements	(292,519)	(346,545)
Netting of cash collateral received	(15,376)	(23,136)
Total trading derivatives, netting	(307,895)	(369,681)
Trading derivatives	66,079	75,306
Recurring | Trading account derivatives | Interest rate contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	167,631	178,204
Recurring | Trading account derivatives | Foreign exchange contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	131,614	187,663
Recurring | Trading account derivatives | Equity contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	40,505	42,407
Recurring | Trading account derivatives | Commodity contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	24,182	28,324
Recurring | Trading account derivatives | Credit derivatives
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	10,042	8,389
Recurring | Non-trading derivatives and other financial assets measured on a recurring basis
Assets, Fair Value Disclosure [Abstract]
Total trading derivatives, netting	0	0
Total other assets and cash collateral, gross	11,847	10,658
Other assets	11,847	10,658
Recurring | Level 1
Assets, Fair Value Disclosure [Abstract]
Federal funds sold and securities borrowed and purchased under agreements to resell	0	0
Investments	139,316	152,754
Loans held at fair value	0	0
Mortgage servicing rights	0	0
Assets before netting	$ 333,142	$ 304,439
Total as a percentage of gross assets	24.80%	23.00%
Liabilities, Fair Value Disclosure [Abstract]
Interest-bearing deposits	$ 0	$ 0
Federal funds purchased and securities loaned and sold under agreements to repurchase, Gross	0	0
Securities sold, not yet purchased	116,243	97,559
Trading liabilities	116,243	97,559
Short-term borrowings	0	0
Long-term debt	0	0
Total liabilities, Gross	$ 121,237	$ 102,003
Total as a percentage of gross liabilities	15.00%	12.40%
Recurring | Level 1 | Trading account liabilities
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	$ 255	$ 247
Recurring | Level 1 | Trading account liabilities | Interest rate contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	185	175
Recurring | Level 1 | Trading account liabilities | Foreign exchange contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	0	0
Recurring | Level 1 | Trading account liabilities | Equity contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	34	70
Recurring | Level 1 | Trading account liabilities | Commodity contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	36	2
Recurring | Level 1 | Trading account liabilities | Credit derivatives
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	0	0
Recurring | Level 1 | Other financial liabilities measured on a recurring basis
Liabilities, Fair Value Disclosure [Abstract]
Other liabilities, gross	4,739	4,197
Recurring | Level 1 | Other trading liabilities
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	0	0
Recurring | Level 1 | Mortgage-backed securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	1	1
Investments	0	0
Recurring | Level 1 | Mortgage securitizations - U.S. agency-sponsored
Assets, Fair Value Disclosure [Abstract]
Trading account assets	0	0
Investments	0	0
Recurring | Level 1 | Residential
Assets, Fair Value Disclosure [Abstract]
Trading account assets	1	1
Investments	0	0
Recurring | Level 1 | Commercial
Assets, Fair Value Disclosure [Abstract]
Trading account assets	0	0
Investments	0	0
Recurring | Level 1 | U.S. Treasury and federal agency securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	96,133	63,067
Investments	86,525	91,851
Recurring | Level 1 | State and municipal
Assets, Fair Value Disclosure [Abstract]
Trading account assets	0	0
Investments	0	0
Recurring | Level 1 | Foreign government
Assets, Fair Value Disclosure [Abstract]
Trading account assets	51,826	38,383
Investments	50,102	58,419
Recurring | Level 1 | Corporate
Assets, Fair Value Disclosure [Abstract]
Trading account assets	1,262	1,593
Investments	2,431	2,230
Recurring | Level 1 | Equity securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	39,629	43,990
Investments	258	254
Recurring | Level 1 | Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	0	0
Investments	0	0
Recurring | Level 1 | Other trading assets
Assets, Fair Value Disclosure [Abstract]
Trading account assets	55	24
Investments	0	0
Recurring | Level 1 | Non-marketable equity securities
Assets, Fair Value Disclosure [Abstract]
Investments	0	0
Recurring | Level 1 | Trading non-derivative assets
Assets, Fair Value Disclosure [Abstract]
Trading account assets	188,906	147,058
Recurring | Level 1 | Trading account derivatives
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	282	317
Recurring | Level 1 | Trading account derivatives | Interest rate contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	225	297
Recurring | Level 1 | Trading account derivatives | Foreign exchange contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	0	0
Recurring | Level 1 | Trading account derivatives | Equity contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	21	20
Recurring | Level 1 | Trading account derivatives | Commodity contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	36	0
Recurring | Level 1 | Trading account derivatives | Credit derivatives
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	0	0
Recurring | Level 1 | Non-trading derivatives and other financial assets measured on a recurring basis
Assets, Fair Value Disclosure [Abstract]
Other assets, gross	4,638	4,310
Recurring | Level 2
Assets, Fair Value Disclosure [Abstract]
Federal funds sold and securities borrowed and purchased under agreements to resell	391,214	350,145
Investments	100,136	95,744
Loans held at fair value	4,494	3,999
Mortgage servicing rights	0	0
Assets before netting	$ 994,564	$ 1,001,032
Total as a percentage of gross assets	74.10%	75.80%
Liabilities, Fair Value Disclosure [Abstract]
Interest-bearing deposits	$ 2,927	$ 1,860
Federal funds purchased and securities loaned and sold under agreements to repurchase, Gross	174,947	155,822
Securities sold, not yet purchased	15,222	13,111
Trading liabilities	15,239	13,119
Short-term borrowings	6,592	6,184
Long-term debt	78,587	69,878
Total liabilities, Gross	$ 639,280	$ 674,144
Total as a percentage of gross liabilities	79.20%	82.00%
Recurring | Level 2 | Trading account liabilities
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	$ 360,864	$ 427,041
Recurring | Level 2 | Trading account liabilities | Interest rate contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	159,732	169,049
Recurring | Level 2 | Trading account liabilities | Foreign exchange contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	127,948	185,279
Recurring | Level 2 | Trading account liabilities | Equity contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	41,568	40,905
Recurring | Level 2 | Trading account liabilities | Commodity contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	22,471	25,093
Recurring | Level 2 | Trading account liabilities | Credit derivatives
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	9,145	6,715
Recurring | Level 2 | Other financial liabilities measured on a recurring basis
Liabilities, Fair Value Disclosure [Abstract]
Other liabilities, gross	124	240
Recurring | Level 2 | Other trading liabilities
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	17	8
Recurring | Level 2 | Mortgage-backed securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	48,573	37,497
Investments	14,905	11,678
Recurring | Level 2 | Mortgage securitizations - U.S. agency-sponsored
Assets, Fair Value Disclosure [Abstract]
Trading account assets	45,404	34,878
Investments	14,588	11,232
Recurring | Level 2 | Residential
Assets, Fair Value Disclosure [Abstract]
Trading account assets	2,442	1,821
Investments	315	444
Recurring | Level 2 | Commercial
Assets, Fair Value Disclosure [Abstract]
Trading account assets	727	798
Investments	2	2
Recurring | Level 2 | U.S. Treasury and federal agency securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	3,667	4,513
Investments	101	439
Recurring | Level 2 | State and municipal
Assets, Fair Value Disclosure [Abstract]
Trading account assets	1,851	2,256
Investments	1,772	1,637
Recurring | Level 2 | Foreign government
Assets, Fair Value Disclosure [Abstract]
Trading account assets	30,459	25,850
Investments	74,431	74,250
Recurring | Level 2 | Corporate
Assets, Fair Value Disclosure [Abstract]
Trading account assets	14,551	11,955
Investments	2,529	2,343
Recurring | Level 2 | Equity securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	10,733	10,179
Investments	173	165
Recurring | Level 2 | Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	1,865	1,597
Investments	1,064	1,029
Recurring | Level 2 | Other trading assets
Assets, Fair Value Disclosure [Abstract]
Trading account assets	13,980	14,963
Investments	5,155	4,194
Recurring | Level 2 | Non-marketable equity securities
Assets, Fair Value Disclosure [Abstract]
Investments	6	9
Recurring | Level 2 | Trading non-derivative assets
Assets, Fair Value Disclosure [Abstract]
Trading account assets	125,679	108,810
Recurring | Level 2 | Trading account derivatives
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	365,884	436,043
Recurring | Level 2 | Trading account derivatives | Interest rate contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	164,020	174,156
Recurring | Level 2 | Trading account derivatives | Foreign exchange contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	130,754	186,897
Recurring | Level 2 | Trading account derivatives | Equity contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	39,069	40,683
Recurring | Level 2 | Trading account derivatives | Commodity contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	22,848	26,823
Recurring | Level 2 | Trading account derivatives | Credit derivatives
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	9,193	7,484
Recurring | Level 2 | Non-trading derivatives and other financial assets measured on a recurring basis
Assets, Fair Value Disclosure [Abstract]
Other assets, gross	7,157	6,291
Recurring | Level 3
Assets, Fair Value Disclosure [Abstract]
Federal funds sold and securities borrowed and purchased under agreements to resell	153	149
Investments	1,893	2,049
Loans held at fair value	640	1,361
Mortgage servicing rights	658	665
Assets before netting	$ 14,446	$ 15,848
Total as a percentage of gross assets	1.10%	1.20%
Liabilities, Fair Value Disclosure [Abstract]
Interest-bearing deposits	$ 16	$ 15
Federal funds purchased and securities loaned and sold under agreements to repurchase, Gross	809	1,031
Securities sold, not yet purchased	72	50
Trading liabilities	73	53
Short-term borrowings	281	38
Long-term debt	36,581	36,117
Total liabilities, Gross	$ 46,625	$ 46,461
Total as a percentage of gross liabilities	5.80%	5.60%
Recurring | Level 3 | Trading account liabilities
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	$ 8,845	$ 9,205
Recurring | Level 3 | Trading account liabilities | Interest rate contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	3,126	3,396
Recurring | Level 3 | Trading account liabilities | Foreign exchange contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	784	716
Recurring | Level 3 | Trading account liabilities | Equity contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	2,997	2,808
Recurring | Level 3 | Trading account liabilities | Commodity contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	1,068	1,223
Recurring | Level 3 | Trading account liabilities | Credit derivatives
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	870	1,062
Recurring | Level 3 | Other financial liabilities measured on a recurring basis
Liabilities, Fair Value Disclosure [Abstract]
Other liabilities, gross	20	2
Recurring | Level 3 | Other trading liabilities
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	1	3
Recurring | Level 3 | Mortgage-backed securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	983	911
Investments	53	71
Recurring | Level 3 | Mortgage securitizations - U.S. agency-sponsored
Assets, Fair Value Disclosure [Abstract]
Trading account assets	658	600
Investments	28	30
Recurring | Level 3 | Residential
Assets, Fair Value Disclosure [Abstract]
Trading account assets	162	166
Investments	25	41
Recurring | Level 3 | Commercial
Assets, Fair Value Disclosure [Abstract]
Trading account assets	163	145
Investments	0	0
Recurring | Level 3 | U.S. Treasury and federal agency securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	1	1
Investments	51	0
Recurring | Level 3 | State and municipal
Assets, Fair Value Disclosure [Abstract]
Trading account assets	23	7
Investments	521	586
Recurring | Level 3 | Foreign government
Assets, Fair Value Disclosure [Abstract]
Trading account assets	53	119
Investments	551	608
Recurring | Level 3 | Corporate
Assets, Fair Value Disclosure [Abstract]
Trading account assets	296	394
Investments	291	343
Recurring | Level 3 | Equity securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	225	192
Investments	12	10
Recurring | Level 3 | Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	567	668
Investments	1	1
Recurring | Level 3 | Other trading assets
Assets, Fair Value Disclosure [Abstract]
Trading account assets	1,094	648
Investments	4	0
Recurring | Level 3 | Non-marketable equity securities
Assets, Fair Value Disclosure [Abstract]
Investments	409	430
Recurring | Level 3 | Trading non-derivative assets
Assets, Fair Value Disclosure [Abstract]
Trading account assets	3,242	2,940
Recurring | Level 3 | Trading account derivatives
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	7,808	8,627
Recurring | Level 3 | Trading account derivatives | Interest rate contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	3,386	3,751
Recurring | Level 3 | Trading account derivatives | Foreign exchange contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	860	766
Recurring | Level 3 | Trading account derivatives | Equity contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	1,415	1,704
Recurring | Level 3 | Trading account derivatives | Commodity contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	1,298	1,501
Recurring | Level 3 | Trading account derivatives | Credit derivatives
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	849	905
Recurring | Level 3 | Non-trading derivatives and other financial assets measured on a recurring basis
Assets, Fair Value Disclosure [Abstract]
Other assets, gross	$ 52	$ 57