FAIR VALUE MEASUREMENT (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
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	$ (991)	$ (2,380)
Transfers into Level 3	(524)	518
Transfers out of Level 3	81	(227)
Purchases	170	160
Sales	(143)	(90)
Settlements	(307)	76
Balance at end of period, asset (liability), net	(1,760)	(1,829)
Unrealized gains (losses) still held	(548)	(29)
Trading account assets and liabilities | Principal transactions
Fair value, Derivative assets (liabilities) measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings	(46)	114
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	839	181
Transfers into Level 3	36	514
Transfers out of Level 3	9	(167)
Purchases	18	91
Sales	(46)	(15)
Settlements	(275)	(279)
Balance at end of period, asset (liability), net	233	298
Unrealized gains (losses) still held	(367)	(43)
Trading account assets and liabilities | Interest rate contracts | Principal transactions
Fair value, Derivative assets (liabilities) measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings	(348)	(27)
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	695
Transfers into Level 3	(11)	10
Transfers out of Level 3	19	(10)
Purchases	1	9
Sales		(7)
Settlements	(13)	40
Balance at end of period, asset (liability), net	829	140
Unrealized gains (losses) still held	211	(128)
Trading account assets and liabilities | Foreign exchange contracts | Principal transactions
Fair value, Derivative assets (liabilities) measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings	138	98
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	(858)	(1,448)
Transfers into Level 3	(518)	(22)
Transfers out of Level 3	52	81
Purchases	150	49
Sales	(94)	(61)
Settlements	(120)	(165)
Balance at end of period, asset (liability), net	(1,236)	(1,474)
Unrealized gains (losses) still held	(225)	(101)
Trading account assets and liabilities | Equity contracts | Principal transactions
Fair value, Derivative assets (liabilities) measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings	152	92
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	(1,393)	(771)
Transfers into Level 3	30	8
Transfers out of Level 3	31	(2)
Purchases		3
Sales		(7)
Settlements	(72)	78
Balance at end of period, asset (liability), net	(1,329)	(637)
Unrealized gains (losses) still held	67	137
Trading account assets and liabilities | Commodity contracts | Principal transactions
Fair value, Derivative assets (liabilities) measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings	75	54
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	(274)	(342)
Transfers into Level 3	(61)	8
Transfers out of Level 3	(30)	(129)
Purchases	1	8
Sales	(3)
Settlements	173	402
Balance at end of period, asset (liability), net	(257)	(156)
Unrealized gains (losses) still held	(234)	106
Trading account assets and liabilities | Credit derivatives | Principal transactions
Fair value, Derivative assets (liabilities) measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings	(63)	(103)
Interest-bearing deposits
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, liability	890	786
Transfers into Level 3, liabilities		22
Issuance, liability		25
Settlements, liability	(25)	(15)
Balance at end of period, liability	935	834
Unrealized gains (losses) still held, liabilities	(19)	(56)
Interest-bearing deposits | Other
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in locations other than principal transactions, liabilities	(70)	(16)
Federal funds purchased and securities loaned or sold under agreements to repurchase
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, liability	902	841
Transfers into Level 3, liabilities		201
Purchases, liability	31
Sales, liability		38
Balance at end of period, liability	940	1,053
Unrealized gains (losses) still held, liabilities	(9)	14
Federal funds purchased and securities loaned or sold under agreements to repurchase | Principal transactions
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings, liabilities	(7)	27
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, liability	590	365
Transfers into Level 3, liabilities	18	20
Transfers out of Level 3, liabilities	(29)	(5)
Sales, liability	150	46
Settlements, liability	(237)	(72)
Balance at end of period, liability	482	335
Unrealized gains (losses) still held, liabilities	(13)	125
Trading account liabilities | Securities sold, not yet purchased | Principal transactions
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings, liabilities	10	19
Short-term borrowings
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, liability	29	112
Issuance, liability	1	1
Settlements, liability	(20)	(18)
Balance at end of period, liability	27	53
Unrealized gains (losses) still held, liabilities		(19)
Short-term borrowings | Principal transactions
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings, liabilities	(17)	42
Long-term debt
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, liability	7,621	6,726
Transfers into Level 3, liabilities	959	635
Transfers out of Level 3, liabilities	(854)	(465)
Issuance, liability	940	284
Sales, liability		(1)
Settlements, liability	(279)	(308)
Balance at end of period, liability	8,646	6,847
Unrealized gains (losses) still held, liabilities	(118)	(113)
Long-term debt | Principal transactions
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings, liabilities	(284)	(9)
Long-term debt | Other
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in locations other than principal transactions, liabilities	25	33
Other financial liabilities
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, liability	10	24
Transfers into Level 3, liabilities		2
Transfers out of Level 3, liabilities		(2)
Purchases, liability		(2)
Issuance, liability	1	2
Sales, liability	(3)
Settlements, liability	(5)	(7)
Balance at end of period, liability	3	16
Unrealized gains (losses) still held, liabilities	(1)
Other financial liabilities | Other
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in locations other than principal transactions, liabilities		1
Trading non-derivative assets
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	15,260	13,823
Transfers into Level 3, assets	1,178	861
Transfers out of Level 3, assets	(1,540)	(1,189)
Purchases, assets	4,440	4,131
Issuance, assets	3	26
Sales, assets	(5,432)	(4,741)
Settlements, assets	(86)	(521)
Balance at end of period, asset	14,210	12,922
Unrealized gains (losses) still held, assets	476	(250)
Trading non-derivative assets | Principal transactions
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings, assets	387	532
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, asset	1,094	1,325
Transfers into Level 3, assets	179	392
Transfers out of Level 3, assets	(385)	(402)
Purchases, assets	154	280
Issuance, assets	3	26
Sales, assets	(321)	(368)
Settlements, assets	(17)	(24)
Balance at end of period, asset	788	1,278
Unrealized gains (losses) still held, assets	10	30
Trading non-derivative assets | U.S. government-sponsored agency guaranteed | Principal transactions
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings, assets	81	49
Trading non-derivative assets | Mortgage-backed securities - Residential
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	2,854	1,805
Transfers into Level 3, assets	74	98
Transfers out of Level 3, assets	(153)	(176)
Purchases, assets	976	727
Sales, assets	(1,164)	(506)
Settlements, assets		(7)
Balance at end of period, asset	2,744	2,112
Unrealized gains (losses) still held, assets	41	56
Trading non-derivative assets | Mortgage-backed securities - Residential | Principal transactions
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings, assets	157	171
Trading non-derivative assets | Mortgage-backed securities - Commercial
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	256	1,119
Transfers into Level 3, assets	35	89
Transfers out of Level 3, assets	(24)	(36)
Purchases, assets	32	67
Sales, assets	(63)	(866)
Settlements, assets		(17)
Balance at end of period, asset	241	410
Unrealized gains (losses) still held, assets	5	1
Trading non-derivative assets | Mortgage-backed securities - Commercial | Principal transactions
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings, assets	5	54
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, asset	4,204	4,249
Transfers into Level 3, assets	288	579
Transfers out of Level 3, assets	(562)	(614)
Purchases, assets	1,162	1,074
Issuance, assets	3	26
Sales, assets	(1,548)	(1,740)
Settlements, assets	(17)	(48)
Balance at end of period, asset	3,773	3,800
Unrealized gains (losses) still held, assets	56	87
Trading non-derivative assets | Mortgage-backed securities | Principal transactions
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings, assets	243	274
Trading non-derivative assets | State and municipal securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	222	195
Transfers into Level 3, assets	11
Transfers out of Level 3, assets	(104)
Purchases, assets	9	19
Sales, assets	(19)	(6)
Balance at end of period, asset	121	209
Unrealized gains (losses) still held, assets	3	2
Trading non-derivative assets | State and municipal securities | Principal transactions
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings, assets	2	1
Trading non-derivative assets | Foreign government
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	416	311
Transfers into Level 3, assets	49	6
Transfers out of Level 3, assets	(85)	(36)
Purchases, assets	138	65
Sales, assets	(139)	(120)
Balance at end of period, asset	373	228
Unrealized gains (losses) still held, assets	(5)	1
Trading non-derivative assets | Foreign government | Principal transactions
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings, assets	(6)	2
Trading non-derivative assets | Corporate
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	1,835	2,030
Transfers into Level 3, assets	187	76
Transfers out of Level 3, assets	(145)	(17)
Purchases, assets	592	568
Sales, assets	(828)	(443)
Settlements, assets	(3)	(374)
Balance at end of period, asset	1,665	1,736
Unrealized gains (losses) still held, assets	(30)	(303)
Trading non-derivative assets | Corporate | Principal transactions
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings, assets	27	(104)
Trading non-derivative assets | Equity securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	1,057	264
Transfers into Level 3, assets	35	23
Transfers out of Level 3, assets	(5)	(63)
Purchases, assets	532	78
Sales, assets	(63)	(60)
Balance at end of period, asset	1,385	279
Unrealized gains (losses) still held, assets	267	23
Trading non-derivative assets | Equity securities | Principal transactions
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings, assets	(171)	37
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, asset	4,342	4,453
Transfers into Level 3, assets	33	38
Transfers out of Level 3, assets	(175)	(32)
Purchases, assets	943	1,583
Sales, assets	(1,971)	(1,856)
Balance at end of period, asset	3,441	4,410
Unrealized gains (losses) still held, assets	164	(53)
Trading non-derivative assets | Asset-backed securities | Principal transactions
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings, assets	269	224
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, asset	3,184	2,321
Transfers into Level 3, assets	575	139
Transfers out of Level 3, assets	(464)	(427)
Purchases, assets	1,064	744
Sales, assets	(864)	(516)
Settlements, assets	(66)	(99)
Balance at end of period, asset	3,452	2,260
Unrealized gains (losses) still held, assets	21	(7)
Trading non-derivative assets | Other trading assets | Principal transactions
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings, assets	23	98
Other financial assets
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	181	2,452
Transfers into Level 3, assets		1
Purchases, assets		138
Issuance, assets	36	290
Sales, assets	(4)	(5)
Settlements, assets	(32)	(484)
Balance at end of period, asset	179	2,428
Unrealized gains (losses) still held, assets	(4)	32
Other financial assets | Other
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	(2)	36
Federal funds sold and securities borrowed or purchased under agreements to resell
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	3,566	5,043
Transfers into Level 3, assets	51	598
Transfers out of Level 3, assets		(1,279)
Settlements, assets	(165)
Balance at end of period, asset	3,451	4,349
Unrealized gains (losses) still held, assets	(1)	(43)
Threshold tenor of repo curves to classify structured reverse repos as level 3	5 years
Federal funds sold and securities borrowed or purchased under agreements to resell | Principal transactions
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in earnings, assets	(1)	(13)
Investments
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	9,741	11,907
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	180	106
Transfers into Level 3, assets	389	3,014
Transfers out of Level 3, assets	(407)	(1,744)
Purchases, assets	1,054	1,546
Sales, assets	(549)	(314)
Settlements, assets	(548)	(510)
Balance at end of period, asset	9,860	14,005
Unrealized gains (losses) still held, assets	20	35
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, asset	187	1,458
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	48	3
Transfers into Level 3, assets	24	1,633
Transfers out of Level 3, assets	(37)	(1,031)
Purchases, assets	17	471
Sales, assets	(39)
Settlements, assets	(1)	(8)
Balance at end of period, asset	199	2,526
Unrealized gains (losses) still held, assets		3
Investments | Mortgage-backed securities - Residential
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	102	205
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	23	9
Transfers into Level 3, assets	13	60
Transfers out of Level 3, assets		(205)
Purchases, assets	17	117
Sales, assets	(125)
Balance at end of period, asset	30	186
Unrealized gains (losses) still held, assets	2	9
Investments | Mortgage-backed securities - Commercial
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Transfers into Level 3, assets	1
Balance at end of period, asset	1
Investments | Mortgage-backed securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	289	1,663
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	71	12
Transfers into Level 3, assets	38	1,693
Transfers out of Level 3, assets	(37)	(1,236)
Purchases, assets	34	588
Sales, assets	(164)
Settlements, assets	(1)	(8)
Balance at end of period, asset	230	2,712
Unrealized gains (losses) still held, assets	2	12
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, asset	8	12
Sales, assets	(1)	(1)
Balance at end of period, asset	7	11
Investments | State and municipal securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	1,643	849
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	36	(17)
Transfers into Level 3, assets	254	7
Transfers out of Level 3, assets	(285)	(117)
Purchases, assets	373	81
Sales, assets	(118)	(55)
Balance at end of period, asset	1,903	748
Unrealized gains (losses) still held, assets	26	(40)
Investments | Foreign government
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	344	383
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	2	1
Transfers into Level 3, assets	22	22
Transfers out of Level 3, assets	(42)	(174)
Purchases, assets	49	130
Sales, assets	(78)	(67)
Settlements, assets	(23)	(27)
Balance at end of period, asset	274	268
Unrealized gains (losses) still held, assets	(4)	(4)
Investments | Corporate
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	285	385
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	(1)	1
Transfers into Level 3, assets	2	100
Transfers out of Level 3, assets	(1)	(12)
Purchases, assets	247	14
Sales, assets	(1)	(143)
Balance at end of period, asset	531	345
Unrealized gains (losses) still held, assets	(2)
Investments | Equity securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	815	773
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	16	2
Transfers into Level 3, assets	6
Purchases, assets	1	1
Sales, assets	(7)	(9)
Balance at end of period, asset	831	767
Unrealized gains (losses) still held, assets	(4)	1
Investments | Asset-backed securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	1,960	2,220
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	8	38
Transfers into Level 3, assets		1,192
Transfers out of Level 3, assets	(42)
Purchases, assets	48	692
Sales, assets	(97)	(17)
Settlements, assets		(310)
Balance at end of period, asset	1,877	3,815
Unrealized gains (losses) still held, assets	1	(70)
Investments | Other debt securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	50	258
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	(1)
Transfers out of Level 3, assets		(205)
Purchases, assets	50
Sales, assets		(1)
Balance at end of period, asset	99	52
Investments | Non-marketable equity securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	4,347	5,364
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	49	69
Transfers into Level 3, assets	67
Purchases, assets	252	40
Sales, assets	(83)	(21)
Settlements, assets	(524)	(165)
Balance at end of period, asset	4,108	5,287
Unrealized gains (losses) still held, assets	1	136
Loans
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	4,143	4,931
Purchases, assets	153	95
Issuance, assets	50	7
Sales, assets	(79)	(63)
Settlements, assets	(97)	(381)
Balance at end of period, asset	4,142	4,514
Unrealized gains (losses) still held, assets	(108)	(26)
Loans | Other
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	(28)	(75)
Mortgage servicing rights
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	2,718	1,942
Issuance, assets	50	172
Sales, assets	28	(1)
Settlements, assets	(96)	(100)
Balance at end of period, asset	2,586	2,203
Unrealized gains (losses) still held, assets	(115)	191
Mortgage servicing rights | Other
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	$ (114)	$ 190