FAIR VALUE MEASUREMENT (Details 2) (Recurring, USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
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	$ 4,701	$ 4,911
Net realized/unrealized gains (losses) included in principal transactions, assets	33	(152)
Transfers into Level 3, assets	25
Transfers out of Level 3, assets	(262)
Transfers in and/or out of Level 3, assets		(1,493)
Balance at end of period, asset	4,497	3,266
Unrealized gains (losses) still held, assets	32	(102)
Trading account assets
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	15,258	19,128
Net realized/unrealized gains (losses) included in principal transactions, assets	420	800
Transfers into Level 3, assets	963
Transfers out of Level 3, assets	(913)
Transfers in and/or out of Level 3, assets		(622)
Purchases, assets	6,947	8,400
Issuance, assets	31
Sales, assets	(5,568)	(5,559)
Settlements, assets	(876)
Balance at end of period, asset	16,262	22,147
Unrealized gains (losses) still held, assets	198	94
Trading account assets | Mortgage-backed securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	2,988	3,577
Net realized/unrealized gains (losses) included in principal transactions, assets	2	295
Transfers into Level 3, assets	445
Transfers out of Level 3, assets	(415)
Transfers in and/or out of Level 3, assets		424
Purchases, assets	1,086	3,469
Issuance, assets	31
Sales, assets	(1,088)	(1,202)
Settlements, assets	(39)
Balance at end of period, asset	3,010	6,563
Unrealized gains (losses) still held, assets	36	114
Trading account 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	861	831
Net realized/unrealized gains (losses) included in principal transactions, assets	50	53
Transfers into Level 3, assets	379
Transfers out of Level 3, assets	(127)
Transfers in and/or out of Level 3, assets		236
Purchases, assets	183	94
Issuance, assets	31
Sales, assets	(225)	(190)
Settlements, assets	(37)
Balance at end of period, asset	1,115	1,024
Unrealized gains (losses) still held, assets	22	43
Trading account assets | Prime
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	759	594
Net realized/unrealized gains (losses) included in principal transactions, assets	46	98
Transfers into Level 3, assets	5
Transfers out of Level 3, assets	(103)
Transfers in and/or out of Level 3, assets		24
Purchases, assets	354	1,153
Sales, assets	(316)	(267)
Settlements, assets	(1)
Balance at end of period, asset	744	1,602
Unrealized gains (losses) still held, assets	11	13
Trading account assets | Alt-A
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	165	385
Net realized/unrealized gains (losses) included in principal transactions, assets	18	12
Transfers into Level 3, assets	3
Transfers out of Level 3, assets	(42)
Transfers in and/or out of Level 3, assets		71
Purchases, assets	69	1,551
Sales, assets	(107)	(73)
Balance at end of period, asset	106	1,946
Unrealized gains (losses) still held, assets	(3)	(1)
Trading account assets | Subprime
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	465	1,125
Net realized/unrealized gains (losses) included in principal transactions, assets	(50)	36
Transfers into Level 3, assets	20
Transfers out of Level 3, assets	(20)
Transfers in and/or out of Level 3, assets		13
Purchases, assets	201	309
Sales, assets	(240)	(367)
Settlements, assets	(1)
Balance at end of period, asset	375	1,116
Unrealized gains (losses) still held, assets	1	10
Trading account assets | Non-U.S. residential
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	120	224
Net realized/unrealized gains (losses) included in principal transactions, assets	5	32
Transfers into Level 3, assets	2
Transfers out of Level 3, assets	(15)
Transfers in and/or out of Level 3, assets		85
Purchases, assets	68	122
Sales, assets	(58)	(173)
Balance at end of period, asset	122	290
Unrealized gains (losses) still held, assets	3	1
Trading account assets | Commercial
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	618	418
Net realized/unrealized gains (losses) included in principal transactions, assets	(67)	64
Transfers into Level 3, assets	36
Transfers out of Level 3, assets	(108)
Transfers in and/or out of Level 3, assets		(5)
Purchases, assets	211	240
Sales, assets	(142)	(132)
Balance at end of period, asset	548	585
Unrealized gains (losses) still held, assets	2	48
Trading account 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, asset	3	72
Net realized/unrealized gains (losses) included in principal transactions, assets		1
Transfers in and/or out of Level 3, assets		(14)
Purchases, assets		3
Sales, assets	(3)	(31)
Balance at end of period, asset		31
Trading account assets | Agency obligations
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	3	72
Net realized/unrealized gains (losses) included in principal transactions, assets		1
Transfers in and/or out of Level 3, assets		(14)
Purchases, assets		3
Sales, assets	(3)	(31)
Balance at end of period, asset		31
Trading account assets | State and municipal securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	252	208
Net realized/unrealized gains (losses) included in principal transactions, assets	(3)	62
Transfers in and/or out of Level 3, assets		(5)
Purchases, assets	22	893
Sales, assets	(48)	(43)
Balance at end of period, asset	223	1,115
Unrealized gains (losses) still held, assets	(4)	31
Trading account assets | Foreign government
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	521	566
Net realized/unrealized gains (losses) included in principal transactions, assets	3	1
Transfers into Level 3, assets	2
Transfers out of Level 3, assets	(263)
Transfers in and/or out of Level 3, assets		(4)
Purchases, assets	710	518
Sales, assets	(140)	(174)
Balance at end of period, asset	833	907
Unrealized gains (losses) still held, assets	4	1
Trading account assets | Corporate
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	3,240	6,006
Net realized/unrealized gains (losses) included in principal transactions, assets	119	169
Transfers into Level 3, assets	327
Transfers out of Level 3, assets	(125)
Transfers in and/or out of Level 3, assets		(484)
Purchases, assets	1,496	1,849
Sales, assets	(595)	(1,454)
Settlements, assets	(699)
Balance at end of period, asset	3,763	6,086
Unrealized gains (losses) still held, assets	121	(47)
Trading account assets | Equity securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	244	776
Net realized/unrealized gains (losses) included in principal transactions, assets	4	56
Transfers into Level 3, assets	18
Transfers out of Level 3, assets	(9)
Transfers in and/or out of Level 3, assets		(511)
Purchases, assets	78	105
Sales, assets	(120)	(121)
Settlements, assets	(24)
Balance at end of period, asset	191	305
Unrealized gains (losses) still held, assets	(3)	30
Trading account assets | Asset-backed securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	5,801	6,618
Net realized/unrealized gains (losses) included in principal transactions, assets	335	218
Transfers into Level 3, assets	17
Transfers out of Level 3, assets	(36)
Transfers in and/or out of Level 3, assets		(59)
Purchases, assets	2,651	1,299
Sales, assets	(3,054)	(2,351)
Settlements, assets	(59)
Balance at end of period, asset	5,655	5,725
Unrealized gains (losses) still held, assets	66	(61)
Trading account assets | Other debt securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	2,209	1,305
Net realized/unrealized gains (losses) included in principal transactions, assets	(40)	(2)
Transfers into Level 3, assets	154
Transfers out of Level 3, assets	(65)
Transfers in and/or out of Level 3, assets		31
Purchases, assets	904	264
Sales, assets	(520)	(183)
Settlements, assets	(55)
Balance at end of period, asset	2,587	1,415
Unrealized gains (losses) still held, assets	(22)	26
Derivatives
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	(250)	(1,383)
Net realized/unrealized gains (losses) included in principal transactions, assets	(807)	(675)
Transfers into Level 3, assets	131
Transfers out of Level 3, assets	367
Transfers in and/or out of Level 3, assets		(327)
Purchases, assets	618
Sales, assets	(489)
Settlements, assets	(531)	1,543
Balance at end of period, asset	(961)	(3,928)
Unrealized gains (losses) still held, assets	(1,590)	(1,219)
Investments:
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	16,797	17,286
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	251	427
Transfers out of Level 3, assets	(782)
Transfers in and/or out of Level 3, assets		114
Purchases, assets	1,237	3,377
Sales, assets	(354)	(1,810)
Settlements, assets	(1,349)
Balance at end of period, asset	15,800	19,394
Unrealized gains (losses) still held, assets	246	562
Investments: | Mortgage-backed securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	687	716
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	9	(4)
Transfers out of Level 3, assets	(647)
Transfers in and/or out of Level 3, assets		345
Purchases, assets	891	20
Sales, assets		(36)
Balance at end of period, asset	940	1,041
Unrealized gains (losses) still held, assets	4	(15)
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	679	22
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	9	(9)
Transfers out of Level 3, assets	(641)
Transfers in and/or out of Level 3, assets		344
Purchases, assets	885	5
Balance at end of period, asset	932	362
Unrealized gains (losses) still held, assets	4	(15)
Investments: | Prime
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	8	166
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets		2
Transfers out of Level 3, assets	(6)
Sales, assets		(18)
Balance at end of period, asset	2	150
Investments: | Alt-A
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset		1
Transfers in and/or out of Level 3, assets		1
Balance at end of period, asset		2
Investments: | Commercial
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset		527
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets		3
Purchases, assets	6	15
Sales, assets		(18)
Balance at end of period, asset	6	527
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	75	17
Transfers out of Level 3, assets	(75)
Sales, assets		(1)
Balance at end of period, asset		16
Investments: | State and municipal securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	667	504
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	(1)	(24)
Transfers in and/or out of Level 3, assets		(93)
Purchases, assets	32	21
Sales, assets	(16)	(27)
Balance at end of period, asset	682	381
Unrealized gains (losses) still held, assets	(7)	(30)
Investments: | Foreign government
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	447	358
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	3	7
Transfers out of Level 3, assets	(17)
Transfers in and/or out of Level 3, assets		64
Purchases, assets	89	50
Sales, assets	(80)	(53)
Settlements, assets	(67)
Balance at end of period, asset	375	426
Unrealized gains (losses) still held, assets	1	5
Investments: | Corporate
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	989	1,018
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	(4)	15
Transfers in and/or out of Level 3, assets		37
Purchases, assets	87	27
Sales, assets	(7)	(12)
Settlements, assets	(3)
Balance at end of period, asset	1,062	1,085
Unrealized gains (losses) still held, assets	1	(4)
Investments: | Equity securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	1,453	2,055
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	45	(29)
Transfers in and/or out of Level 3, assets		(29)
Sales, assets	(172)	(168)
Balance at end of period, asset	1,326	1,829
Unrealized gains (losses) still held, assets	16	62
Investments: | Asset-backed securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	4,041	5,424
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	3	46
Transfers out of Level 3, assets	(43)
Transfers in and/or out of Level 3, assets		43
Purchases, assets		36
Sales, assets	(7)	(547)
Settlements, assets	(921)
Balance at end of period, asset	3,073	5,002
Unrealized gains (losses) still held, assets		26
Investments: | Other debt securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	120	727
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets		(33)
Transfers in and/or out of Level 3, assets		67
Purchases, assets		33
Sales, assets	(64)	(122)
Settlements, assets	(1)
Balance at end of period, asset	55	672
Unrealized gains (losses) still held, assets		(33)
Investments: | Non-marketable equity securities
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	8,318	6,467
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	196	449
Transfers in and/or out of Level 3, assets		(320)
Purchases, assets	138	3,190
Sales, assets	(8)	(844)
Settlements, assets	(357)
Balance at end of period, asset	8,287	8,942
Unrealized gains (losses) still held, assets	231	551
Loans
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	4,682	3,213
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	(37)	(87)
Transfers out of Level 3, assets	(25)
Transfers in and/or out of Level 3, assets		(19)
Purchases, assets	86
Issuance, assets		341
Sales, assets	(8)
Settlements, assets	(420)	296
Balance at end of period, asset	4,278	3,152
Unrealized gains (losses) still held, assets	300	(112)
Mortgage servicing rights
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	2,569	4,554
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	187	208
Purchases, assets	2
Issuance, assets	142
Sales, assets	(5)
Settlements, assets	(204)	72
Balance at end of period, asset	2,691	4,690
Unrealized gains (losses) still held, assets	184	208
Other financial assets measured on a recurring basis
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	2,245	2,509
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets	7	(16)
Transfers into Level 3, assets	8
Transfers out of Level 3, assets	(1)
Transfers in and/or out of Level 3, assets		(19)
Purchases, assets	1
Issuance, assets	276	201
Sales, assets	(38)
Settlements, assets	(176)	190
Balance at end of period, asset	2,322	2,485
Unrealized gains (losses) still held, assets	14	8
Interest-bearing deposits
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, liability	431	277
Net realized/unrealized gains (losses) included in locations other than principal transactions, liabilities	(5)	(34)
Transfers in and/or out of Level 3, liabilities		60
Issuance, liability	8	215
Settlements, liability	(69)	(1)
Balance at end of period, liability	458	585
Unrealized gains (losses) still held, liabilities	(58)	91
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	1,061	1,261
Net realized/unrealized gains (losses) included in principal transactions, liabilities	27	18
Transfers in and/or out of Level 3, liabilities		90
Sales, liability		(165)
Settlements, liability	(9)
Balance at end of period, liability	1,025	1,168
Unrealized gains (losses) still held, liabilities		(15)
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	412	187
Net realized/unrealized gains (losses) included in principal transactions, liabilities	(72)	63
Transfers into Level 3, liabilities	4
Transfers out of Level 3, liabilities	(7)
Transfers in and/or out of Level 3, liabilities		(82)
Sales, liability	(71)
Settlements, liability	(375)	67
Balance at end of period, liability	177	109
Unrealized gains (losses) still held, liabilities	(75)	63
Short-term borrowings
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, liability	499	802
Net realized/unrealized gains (losses) included in principal transactions, liabilities	(56)	178
Transfers out of Level 3, liabilities	(9)
Transfers in and/or out of Level 3, liabilities		(41)
Issuance, liability	126	25
Settlements, liability	(249)	(217)
Balance at end of period, liability	423	391
Unrealized gains (losses) still held, liabilities	(2)	52
Long-term debt
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, liability	6,904	8,494
Net realized/unrealized gains (losses) included in principal transactions, liabilities	(78)	(71)
Net realized/unrealized gains (losses) included in locations other than principal transactions, liabilities	29	96
Transfers into Level 3, liabilities	159
Transfers out of Level 3, liabilities	(416)
Transfers in and/or out of Level 3, liabilities		25
Issuance, liability	287	463
Settlements, liability	(464)	(165)
Balance at end of period, liability	6,519	8,792
Unrealized gains (losses) still held, liabilities	(203)	(301)
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, liability	3	19
Net realized/unrealized gains (losses) included in locations other than principal transactions, liabilities	(1)	(4)
Transfers in and/or out of Level 3, liabilities		7
Purchases, liability	1
Issuance, liability		4
Settlements, liability	(1)	(25)
Balance at end of period, liability	2	9
Unrealized gains (losses) still held, liabilities	(1)	5
Interest rate contracts | Derivatives
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	726	(730)
Net realized/unrealized gains (losses) included in principal transactions, assets	(217)	(243)
Transfers into Level 3, assets	342
Transfers out of Level 3, assets	(17)
Transfers in and/or out of Level 3, assets		724
Purchases, assets	199
Sales, assets	(129)
Settlements, assets	(213)	(253)
Balance at end of period, asset	691	4
Unrealized gains (losses) still held, assets	(456)	(486)
Foreign exchange contracts | Derivatives
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	(33)	164
Net realized/unrealized gains (losses) included in principal transactions, assets	97	141
Transfers into Level 3, assets	(5)
Transfers out of Level 3, assets	(8)
Transfers in and/or out of Level 3, assets		(42)
Purchases, assets	129
Sales, assets	(107)
Settlements, assets	(17)	24
Balance at end of period, asset	56	239
Unrealized gains (losses) still held, assets	29	(3)
Equity contracts | Derivatives
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	(1,737)	(1,639)
Net realized/unrealized gains (losses) included in principal transactions, assets	474	24
Transfers into Level 3, assets	3
Transfers out of Level 3, assets	436
Transfers in and/or out of Level 3, assets		(743)
Purchases, assets	134
Sales, assets	(175)
Settlements, assets	(212)	210
Balance at end of period, asset	(1,077)	(2,568)
Unrealized gains (losses) still held, assets	(135)	(253)
Commodity and other contracts | Derivatives
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	(934)	(1,023)
Net realized/unrealized gains (losses) included in principal transactions, assets	74	(59)
Transfers into Level 3, assets	(5)
Transfers out of Level 3, assets	9
Transfers in and/or out of Level 3, assets		(88)
Purchases, assets	45
Sales, assets	(68)
Settlements, assets	20	126
Balance at end of period, asset	(859)	(1,296)
Unrealized gains (losses) still held, assets	2	(143)
Credit derivatives | Derivatives
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset	1,728	1,845
Net realized/unrealized gains (losses) included in principal transactions, assets	(1,235)	(538)
Transfers into Level 3, assets	(204)
Transfers out of Level 3, assets	(53)
Transfers in and/or out of Level 3, assets		(178)
Purchases, assets	111
Sales, assets	(10)
Settlements, assets	(109)	1,436
Balance at end of period, asset	228	(307)
Unrealized gains (losses) still held, assets	$ (1,030)	$ (334)