FAIR VALUE MEASUREMENT - Items Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Assets, Fair Value Disclosure [Abstract]
Federal funds sold and securities borrowed and purchased under agreements to resell, Netting	$ (219,046)	$ (112,391)
Trading account assets	423,189	334,114
Netting agreements	(312,754)	(346,545)
Netting of cash collateral received	(18,645)	(23,136)
Trading derivatives	71,601	75,306
Investments	507,145	526,582
Loans held at fair value	5,766	5,360
Liabilities, Fair Value Disclosure [Abstract]
Federal funds purchased and securities loaned and sold under agreements to repurchase, Netting	(219,046)	(112,391)
Netting agreements	(312,754)	(346,545)
Netting of cash collateral paid	(28,221)	(30,032)
Total derivative liabilities	56,040	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	24	27
Recurring
Assets, Fair Value Disclosure [Abstract]
Federal funds sold and securities borrowed and purchased under agreements to resell	428,314	350,294
Federal funds sold and securities borrowed and purchased under agreements to resell, Netting	(218,188)	(110,767)
Federal funds sold and securities borrowed and purchased under agreements to resell	210,126	239,527
Investments	238,039	250,547
Loans held at fair value	5,766	5,360
Mortgage servicing rights	681	665
Assets before netting	1,441,025	1,321,319
Netting, Assets, total of netting agreements and cash collateral received	(549,587)	(480,448)
Total assets	891,438	840,871
Liabilities, Fair Value Disclosure [Abstract]
Interest-bearing deposits	2,598	1,875
Federal funds purchased and securities loaned and sold under agreements to repurchase, Gross	214,431	156,853
Federal funds purchased and securities loaned and sold under agreements to repurchase, Netting	(151,631)	(85,967)
Federal funds purchased and securities loaned and sold under agreements to repurchase	62,800	70,886
Securities sold, not yet purchased	114,616	110,720
Trading liabilities	114,624	110,731
Short-term borrowings	5,622	6,222
Long-term debt	115,937	105,995
Total liabilities, Gross	856,216	822,608
Total liabilities, Netting	(492,606)	(462,544)
Total liabilities	363,610	360,064
Recurring | Trading account liabilities
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	397,015	436,493
Total trading derivatives and cash collateral, liability	397,015	436,493
Netting agreements	(312,754)	(346,545)
Netting of cash collateral paid	(28,221)	(30,032)
Netting, Liabilities, total of netting agreements and cash collateral received	(340,975)	(376,577)
Total derivative liabilities	56,040	59,916
Recurring | Trading account liabilities | Interest rate contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	164,211	172,620
Recurring | Trading account liabilities | Foreign exchange contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	152,825	185,995
Recurring | Trading account liabilities | Equity contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	51,581	43,783
Recurring | Trading account liabilities | Commodity contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	17,670	26,318
Recurring | Trading account liabilities | Credit derivatives
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	10,728	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	5,989	4,439
Total other assets and cash collateral, gross	5,989	4,439
Recurring | Other trading liabilities
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	8	11
Recurring | Mortgage-backed securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	60,006	38,409
Investments	15,302	11,749
Recurring | Mortgage securitizations - U.S. agency-sponsored
Assets, Fair Value Disclosure [Abstract]
Trading account assets	55,958	35,478
Investments	14,963	11,262
Recurring | Residential
Assets, Fair Value Disclosure [Abstract]
Trading account assets	3,082	1,988
Investments	337	485
Recurring | Commercial
Assets, Fair Value Disclosure [Abstract]
Trading account assets	966	943
Investments	2	2
Recurring | U.S. Treasury and federal agency securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	90,594	67,581
Investments	82,243	92,290
Recurring | State and municipal
Assets, Fair Value Disclosure [Abstract]
Trading account assets	2,095	2,263
Investments	2,202	2,223
Recurring | Foreign government
Assets, Fair Value Disclosure [Abstract]
Trading account assets	92,216	64,352
Investments	125,270	133,277
Recurring | Corporate
Assets, Fair Value Disclosure [Abstract]
Trading account assets	18,899	13,942
Investments	5,327	4,916
Recurring | Equity securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	67,583	54,361
Investments	296	429
Recurring | Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	2,099	2,265
Investments	846	1,030
Recurring | Other debt securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	18,096	15,635
Investments	6,144	4,194
Recurring | Non-marketable equity securities
Assets, Fair Value Disclosure [Abstract]
Investments	409	439
Recurring | Trading non-derivative assets
Assets, Fair Value Disclosure [Abstract]
Trading account assets	351,588	258,808
Recurring | Trading account derivatives
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	403,000	444,987
Trading derivative, asset, gross net cash collateral paid	403,000	444,987
Netting agreements	(312,754)	(346,545)
Netting of cash collateral received	(18,645)	(23,136)
Total trading derivatives, netting	(331,399)	(369,681)
Trading derivatives	71,601	75,306
Recurring | Trading account derivatives | Interest rate contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	168,694	178,204
Recurring | Trading account derivatives | Foreign exchange contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	159,856	187,663
Recurring | Trading account derivatives | Equity contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	47,085	42,407
Recurring | Trading account derivatives | Commodity contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	16,526	28,324
Recurring | Trading account derivatives | Credit derivatives
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	10,839	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	13,637	10,658
Other assets	13,637	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	135,560	152,754
Loans held at fair value	0	0
Mortgage servicing rights	0	0
Assets before netting	$ 343,367	$ 304,439
Total as a percentage of gross assets	23.80%	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	98,359	97,559
Trading liabilities	98,359	97,559
Short-term borrowings	0	0
Long-term debt	0	0
Total liabilities, Gross	$ 104,198	$ 102,003
Total as a percentage of gross liabilities	12.20%	12.40%
Recurring | Level 1 | Trading account liabilities
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	$ 46	$ 247
Recurring | Level 1 | Trading account liabilities | Interest rate contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	19	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	27	70
Recurring | Level 1 | Trading account liabilities | Commodity contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	0	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	5,793	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	88,273	63,067
Investments	81,878	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	56,090	38,383
Investments	50,928	58,419
Recurring | Level 1 | Corporate
Assets, Fair Value Disclosure [Abstract]
Trading account assets	1,695	1,593
Investments	2,590	2,230
Recurring | Level 1 | Equity securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	55,898	43,990
Investments	164	254
Recurring | Level 1 | Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	0	0
Investments	0	0
Recurring | Level 1 | Other debt securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	5	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	201,962	147,058
Recurring | Level 1 | Trading account derivatives
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	52	317
Recurring | Level 1 | Trading account derivatives | Interest rate contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	21	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	31	20
Recurring | Level 1 | Trading account derivatives | Commodity contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	0	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	5,793	4,310
Recurring | Level 2
Assets, Fair Value Disclosure [Abstract]
Federal funds sold and securities borrowed and purchased under agreements to resell	428,174	350,145
Investments	100,715	95,744
Loans held at fair value	5,525	3,999
Mortgage servicing rights	0	0
Assets before netting	$ 1,083,784	$ 1,001,032
Total as a percentage of gross assets	75.20%	75.80%
Liabilities, Fair Value Disclosure [Abstract]
Interest-bearing deposits	$ 2,572	$ 1,860
Federal funds purchased and securities loaned and sold under agreements to repurchase, Gross	213,804	155,822
Securities sold, not yet purchased	16,195	13,111
Trading liabilities	16,199	13,119
Short-term borrowings	5,326	6,184
Long-term debt	78,733	69,878
Total liabilities, Gross	$ 704,104	$ 674,144
Total as a percentage of gross liabilities	82.20%	82.00%
Recurring | Level 2 | Trading account liabilities
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	$ 387,297	$ 427,041
Recurring | Level 2 | Trading account liabilities | Interest rate contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	159,959	169,049
Recurring | Level 2 | Trading account liabilities | Foreign exchange contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	152,029	185,279
Recurring | Level 2 | Trading account liabilities | Equity contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	48,699	40,905
Recurring | Level 2 | Trading account liabilities | Commodity contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	16,892	25,093
Recurring | Level 2 | Trading account liabilities | Credit derivatives
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	9,718	6,715
Recurring | Level 2 | Other financial liabilities measured on a recurring basis
Liabilities, Fair Value Disclosure [Abstract]
Other liabilities, gross	173	240
Recurring | Level 2 | Other trading liabilities
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	4	8
Recurring | Level 2 | Mortgage-backed securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	59,019	37,497
Investments	15,245	11,678
Recurring | Level 2 | Mortgage securitizations - U.S. agency-sponsored
Assets, Fair Value Disclosure [Abstract]
Trading account assets	55,299	34,878
Investments	14,931	11,232
Recurring | Level 2 | Residential
Assets, Fair Value Disclosure [Abstract]
Trading account assets	2,936	1,821
Investments	312	444
Recurring | Level 2 | Commercial
Assets, Fair Value Disclosure [Abstract]
Trading account assets	784	798
Investments	2	2
Recurring | Level 2 | U.S. Treasury and federal agency securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	2,321	4,513
Investments	344	439
Recurring | Level 2 | State and municipal
Assets, Fair Value Disclosure [Abstract]
Trading account assets	2,092	2,256
Investments	1,695	1,637
Recurring | Level 2 | Foreign government
Assets, Fair Value Disclosure [Abstract]
Trading account assets	36,045	25,850
Investments	73,928	74,250
Recurring | Level 2 | Corporate
Assets, Fair Value Disclosure [Abstract]
Trading account assets	16,623	11,955
Investments	2,447	2,343
Recurring | Level 2 | Equity securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	11,400	10,179
Investments	119	165
Recurring | Level 2 | Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	1,560	1,597
Investments	845	1,029
Recurring | Level 2 | Other debt securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	16,613	14,963
Investments	6,087	4,194
Recurring | Level 2 | Non-marketable equity securities
Assets, Fair Value Disclosure [Abstract]
Investments	5	9
Recurring | Level 2 | Trading non-derivative assets
Assets, Fair Value Disclosure [Abstract]
Trading account assets	145,673	108,810
Recurring | Level 2 | Trading account derivatives
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	395,926	436,043
Recurring | Level 2 | Trading account derivatives | Interest rate contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	166,402	174,156
Recurring | Level 2 | Trading account derivatives | Foreign exchange contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	158,360	186,897
Recurring | Level 2 | Trading account derivatives | Equity contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	45,762	40,683
Recurring | Level 2 | Trading account derivatives | Commodity contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	15,418	26,823
Recurring | Level 2 | Trading account derivatives | Credit derivatives
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	9,984	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	7,771	6,291
Recurring | Level 3
Assets, Fair Value Disclosure [Abstract]
Federal funds sold and securities borrowed and purchased under agreements to resell	140	149
Investments	1,764	2,049
Loans held at fair value	241	1,361
Mortgage servicing rights	681	665
Assets before netting	$ 13,874	$ 15,848
Total as a percentage of gross assets	1.00%	1.20%
Liabilities, Fair Value Disclosure [Abstract]
Interest-bearing deposits	$ 26	$ 15
Federal funds purchased and securities loaned and sold under agreements to repurchase, Gross	627	1,031
Securities sold, not yet purchased	62	50
Trading liabilities	66	53
Short-term borrowings	296	38
Long-term debt	37,204	36,117
Total liabilities, Gross	$ 47,914	$ 46,461
Total as a percentage of gross liabilities	5.60%	5.60%
Recurring | Level 3 | Trading account liabilities
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	$ 9,672	$ 9,205
Recurring | Level 3 | Trading account liabilities | Interest rate contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	4,233	3,396
Recurring | Level 3 | Trading account liabilities | Foreign exchange contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	796	716
Recurring | Level 3 | Trading account liabilities | Equity contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	2,855	2,808
Recurring | Level 3 | Trading account liabilities | Commodity contracts
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	778	1,223
Recurring | Level 3 | Trading account liabilities | Credit derivatives
Liabilities, Fair Value Disclosure [Abstract]
Trading derivatives, liability	1,010	1,062
Recurring | Level 3 | Other financial liabilities measured on a recurring basis
Liabilities, Fair Value Disclosure [Abstract]
Other liabilities, gross	23	2
Recurring | Level 3 | Other trading liabilities
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	4	3
Recurring | Level 3 | Mortgage-backed securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	986	911
Investments	57	71
Recurring | Level 3 | Mortgage securitizations - U.S. agency-sponsored
Assets, Fair Value Disclosure [Abstract]
Trading account assets	659	600
Investments	32	30
Recurring | Level 3 | Residential
Assets, Fair Value Disclosure [Abstract]
Trading account assets	145	166
Investments	25	41
Recurring | Level 3 | Commercial
Assets, Fair Value Disclosure [Abstract]
Trading account assets	182	145
Investments	0	0
Recurring | Level 3 | U.S. Treasury and federal agency securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	0	1
Investments	21	0
Recurring | Level 3 | State and municipal
Assets, Fair Value Disclosure [Abstract]
Trading account assets	3	7
Investments	507	586
Recurring | Level 3 | Foreign government
Assets, Fair Value Disclosure [Abstract]
Trading account assets	81	119
Investments	414	608
Recurring | Level 3 | Corporate
Assets, Fair Value Disclosure [Abstract]
Trading account assets	581	394
Investments	290	343
Recurring | Level 3 | Equity securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	285	192
Investments	13	10
Recurring | Level 3 | Asset-backed securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	539	668
Investments	1	1
Recurring | Level 3 | Other debt securities
Assets, Fair Value Disclosure [Abstract]
Trading account assets	1,478	648
Investments	57	0
Recurring | Level 3 | Non-marketable equity securities
Assets, Fair Value Disclosure [Abstract]
Investments	404	430
Recurring | Level 3 | Trading non-derivative assets
Assets, Fair Value Disclosure [Abstract]
Trading account assets	3,953	2,940
Recurring | Level 3 | Trading account derivatives
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	7,022	8,627
Recurring | Level 3 | Trading account derivatives | Interest rate contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	2,271	3,751
Recurring | Level 3 | Trading account derivatives | Foreign exchange contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	1,496	766
Recurring | Level 3 | Trading account derivatives | Equity contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	1,292	1,704
Recurring | Level 3 | Trading account derivatives | Commodity contracts
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	1,108	1,501
Recurring | Level 3 | Trading account derivatives | Credit derivatives
Assets, Fair Value Disclosure [Abstract]
Trading derivatives, asset, Gross	855	905
Recurring | Level 3 | Non-trading derivatives and other financial assets measured on a recurring basis
Assets, Fair Value Disclosure [Abstract]
Other assets, gross	$ 73	$ 57