FAIR VALUE MEASUREMENT (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended			3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2013 Interest-bearing deposits Recurring	Jun. 30, 2012 Interest-bearing deposits Recurring	Jun. 30, 2013 Interest-bearing deposits Recurring	Jun. 30, 2012 Interest-bearing deposits Recurring	Jun. 30, 2013 Federal funds purchased and securities loaned or sold under agreements to repurchase Recurring	Jun. 30, 2012 Federal funds purchased and securities loaned or sold under agreements to repurchase Recurring	Jun. 30, 2013 Federal funds purchased and securities loaned or sold under agreements to repurchase Recurring	Jun. 30, 2012 Federal funds purchased and securities loaned or sold under agreements to repurchase Recurring	Jun. 30, 2013 Trading account liabilities Securities sold, not yet purchased Recurring	Jun. 30, 2012 Trading account liabilities Securities sold, not yet purchased Recurring	Jun. 30, 2013 Trading account liabilities Securities sold, not yet purchased Recurring	Jun. 30, 2012 Trading account liabilities Securities sold, not yet purchased Recurring	Jun. 30, 2013 Short-term borrowings Recurring	Jun. 30, 2012 Short-term borrowings Recurring	Jun. 30, 2013 Short-term borrowings Recurring	Jun. 30, 2012 Short-term borrowings Recurring	Jun. 30, 2013 Long-term debt Recurring	Jun. 30, 2012 Long-term debt Recurring	Jun. 30, 2013 Long-term debt Recurring	Jun. 30, 2012 Long-term debt Recurring	Jun. 30, 2013 Other financial liabilities measured on a recurring basis Recurring	Jun. 30, 2012 Other financial liabilities measured on a recurring basis Recurring	Jun. 30, 2013 Other financial liabilities measured on a recurring basis Recurring	Jun. 30, 2012 Other financial liabilities measured on a recurring basis Recurring	Jun. 30, 2013 Federal funds sold and securities borrowed or purchased under agreements to resell	Jun. 30, 2013 Federal funds sold and securities borrowed or purchased under agreements to resell Recurring	Jun. 30, 2012 Federal funds sold and securities borrowed or purchased under agreements to resell Recurring	Jun. 30, 2013 Federal funds sold and securities borrowed or purchased under agreements to resell Recurring	Jun. 30, 2012 Federal funds sold and securities borrowed or purchased under agreements to resell Recurring	Jun. 30, 2013 Trading account assets Recurring	Jun. 30, 2012 Trading account assets Recurring	Jun. 30, 2013 Trading account assets Recurring	Jun. 30, 2012 Trading account assets Recurring	Jun. 30, 2013 Trading account assets Mortgage-backed securities Recurring	Jun. 30, 2012 Trading account assets Mortgage-backed securities Recurring	Jun. 30, 2013 Trading account assets Mortgage-backed securities Recurring	Jun. 30, 2012 Trading account assets Mortgage-backed securities Recurring	Jun. 30, 2013 Trading account assets U.S. government-sponsored agency guaranteed Recurring	Jun. 30, 2012 Trading account assets U.S. government-sponsored agency guaranteed Recurring	Jun. 30, 2013 Trading account assets U.S. government-sponsored agency guaranteed Recurring	Jun. 30, 2012 Trading account assets U.S. government-sponsored agency guaranteed Recurring	Jun. 30, 2013 Trading account assets Residential Recurring	Jun. 30, 2012 Trading account assets Residential Recurring	Jun. 30, 2013 Trading account assets Residential Recurring	Jun. 30, 2012 Trading account assets Residential Recurring	Jun. 30, 2013 Trading account assets Commercial Recurring	Jun. 30, 2012 Trading account assets Commercial Recurring	Jun. 30, 2013 Trading account assets Commercial Recurring	Jun. 30, 2012 Trading account assets Commercial Recurring	Jun. 30, 2012 Trading account assets U.S. Treasury and federal agency securities Recurring	Jun. 30, 2012 Trading account assets U.S. Treasury and federal agency securities Recurring	Jun. 30, 2013 Trading account assets State and municipal securities Recurring	Jun. 30, 2012 Trading account assets State and municipal securities Recurring	Jun. 30, 2013 Trading account assets State and municipal securities Recurring	Jun. 30, 2012 Trading account assets State and municipal securities Recurring	Jun. 30, 2013 Trading account assets Foreign government Recurring	Jun. 30, 2012 Trading account assets Foreign government Recurring	Jun. 30, 2013 Trading account assets Foreign government Recurring	Jun. 30, 2012 Trading account assets Foreign government Recurring	Jun. 30, 2013 Trading account assets Corporate Recurring	Jun. 30, 2012 Trading account assets Corporate Recurring	Jun. 30, 2013 Trading account assets Corporate Recurring	Jun. 30, 2012 Trading account assets Corporate Recurring	Jun. 30, 2013 Trading account assets Equity securities Recurring	Jun. 30, 2012 Trading account assets Equity securities Recurring	Jun. 30, 2013 Trading account assets Equity securities Recurring	Jun. 30, 2012 Trading account assets Equity securities Recurring	Jun. 30, 2013 Trading account assets Asset-backed securities Recurring	Jun. 30, 2012 Trading account assets Asset-backed securities Recurring	Jun. 30, 2013 Trading account assets Asset-backed securities Recurring	Jun. 30, 2012 Trading account assets Asset-backed securities Recurring	Jun. 30, 2013 Trading account assets Other debt securities Recurring	Jun. 30, 2012 Trading account assets Other debt securities Recurring	Jun. 30, 2013 Trading account assets Other debt securities Recurring	Jun. 30, 2012 Trading account assets Other debt securities Recurring	Jun. 30, 2013 Derivatives Recurring	Jun. 30, 2012 Derivatives Recurring	Jun. 30, 2013 Derivatives Recurring	Jun. 30, 2012 Derivatives Recurring	Jun. 30, 2013 Investments: Recurring	Jun. 30, 2012 Investments: Recurring	Jun. 30, 2013 Investments: Recurring	Jun. 30, 2012 Investments: Recurring	Jun. 30, 2013 Investments: Mortgage-backed securities Recurring	Jun. 30, 2012 Investments: Mortgage-backed securities Recurring	Jun. 30, 2013 Investments: Mortgage-backed securities Recurring	Jun. 30, 2012 Investments: Mortgage-backed securities Recurring	Jun. 30, 2013 Investments: U.S. government-sponsored agency guaranteed Recurring	Jun. 30, 2012 Investments: U.S. government-sponsored agency guaranteed Recurring	Jun. 30, 2013 Investments: U.S. government-sponsored agency guaranteed Recurring	Jun. 30, 2012 Investments: U.S. government-sponsored agency guaranteed Recurring	Jun. 30, 2013 Investments: Residential Recurring	Jun. 30, 2012 Investments: Residential Recurring	Jun. 30, 2013 Investments: Residential Recurring	Jun. 30, 2012 Investments: Residential Recurring	Jun. 30, 2013 Investments: Commercial Recurring	Jun. 30, 2012 Investments: Commercial Recurring	Jun. 30, 2013 Investments: Commercial Recurring	Jun. 30, 2012 Investments: Commercial Recurring	Jun. 30, 2013 Investments: U.S. Treasury and federal agency securities Recurring	Jun. 30, 2013 Investments: U.S. Treasury and federal agency securities Recurring	Jun. 30, 2012 Investments: U.S. Treasury and federal agency securities Recurring	Jun. 30, 2013 Investments: State and municipal securities Recurring	Jun. 30, 2012 Investments: State and municipal securities Recurring	Jun. 30, 2013 Investments: State and municipal securities Recurring	Jun. 30, 2012 Investments: State and municipal securities Recurring	Jun. 30, 2013 Investments: Foreign government Recurring	Jun. 30, 2012 Investments: Foreign government Recurring	Jun. 30, 2013 Investments: Foreign government Recurring	Jun. 30, 2012 Investments: Foreign government Recurring	Jun. 30, 2013 Investments: Corporate Recurring	Jun. 30, 2012 Investments: Corporate Recurring	Jun. 30, 2013 Investments: Corporate Recurring	Jun. 30, 2012 Investments: Corporate Recurring	Jun. 30, 2013 Investments: Equity securities Recurring	Jun. 30, 2012 Investments: Equity securities Recurring	Jun. 30, 2013 Investments: Equity securities Recurring	Jun. 30, 2012 Investments: Equity securities Recurring	Jun. 30, 2013 Investments: Asset-backed securities Recurring	Jun. 30, 2012 Investments: Asset-backed securities Recurring	Jun. 30, 2013 Investments: Asset-backed securities Recurring	Jun. 30, 2012 Investments: Asset-backed securities Recurring	Jun. 30, 2013 Investments: Other debt securities Recurring	Jun. 30, 2013 Investments: Other debt securities Recurring	Jun. 30, 2012 Investments: Other debt securities Recurring	Mar. 31, 2012 Investments: Other debt securities Recurring	Jun. 30, 2013 Investments: Non-marketable equity securities Recurring	Jun. 30, 2012 Investments: Non-marketable equity securities Recurring	Jun. 30, 2013 Investments: Non-marketable equity securities Recurring	Jun. 30, 2012 Investments: Non-marketable equity securities Recurring	Jun. 30, 2013 Loans Recurring	Jun. 30, 2012 Loans Recurring	Jun. 30, 2013 Loans Recurring	Jun. 30, 2012 Loans Recurring	Jun. 30, 2013 Mortgage servicing rights Recurring	Jun. 30, 2012 Mortgage servicing rights Recurring	Jun. 30, 2013 Mortgage servicing rights Recurring	Jun. 30, 2012 Mortgage servicing rights Recurring	Jun. 30, 2013 Other financial assets measured on a recurring basis Recurring	Jun. 30, 2012 Other financial assets measured on a recurring basis Recurring	Jun. 30, 2013 Other financial assets measured on a recurring basis Recurring	Jun. 30, 2012 Other financial assets measured on a recurring basis Recurring	Jun. 30, 2013 Interest rate contracts Derivatives Recurring	Jun. 30, 2012 Interest rate contracts Derivatives Recurring	Jun. 30, 2013 Interest rate contracts Derivatives Recurring	Jun. 30, 2012 Interest rate contracts Derivatives Recurring	Jun. 30, 2013 Foreign exchange contracts Derivatives Recurring	Jun. 30, 2012 Foreign exchange contracts Derivatives Recurring	Jun. 30, 2013 Foreign exchange contracts Derivatives Recurring	Jun. 30, 2012 Foreign exchange contracts Derivatives Recurring	Jun. 30, 2013 Equity contracts Derivatives Recurring	Jun. 30, 2012 Equity contracts Derivatives Recurring	Jun. 30, 2013 Equity contracts Derivatives Recurring	Jun. 30, 2012 Equity contracts Derivatives Recurring	Jun. 30, 2013 Commodity and other contracts Derivatives Recurring	Jun. 30, 2012 Commodity and other contracts Derivatives Recurring	Jun. 30, 2013 Commodity and other contracts Derivatives Recurring	Jun. 30, 2012 Commodity and other contracts Derivatives Recurring	Jun. 30, 2013 Credit derivatives Derivatives Recurring	Jun. 30, 2012 Credit derivatives Derivatives Recurring	Jun. 30, 2013 Credit derivatives Derivatives Recurring	Jun. 30, 2012 Credit derivatives Derivatives Recurring
Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, asset																										$ 4,349	$ 4,497	$ 5,043	$ 4,701	$ 12,922	$ 16,688	$ 13,823	$ 15,792	$ 3,800	$ 3,010	$ 4,249	$ 2,988	$ 1,278	$ 1,115	$ 1,325	$ 861	$ 2,112	$ 1,347	$ 1,805	$ 1,509	$ 410	$ 548	$ 1,119	$ 618		$ 3	$ 209	$ 223	$ 195	$ 252	$ 228	$ 833	$ 311	$ 521	$ 1,736	$ 3,763	$ 2,030	$ 3,240	$ 279	$ 191	$ 264	$ 244	$ 4,410	$ 5,655	$ 4,453	$ 5,801	$ 2,260	$ 3,013	$ 2,321	$ 2,743	$ (1,829)	$ (1,387)	$ (2,380)	$ (779)	$ 14,005	$ 15,800	$ 11,907	$ 16,797	$ 2,712	$ 940	$ 1,663	$ 687	$ 2,526	$ 932	$ 1,458	$ 679	$ 186	$ 2	$ 205	$ 8		$ 6			$ 11	$ 12	$ 75	$ 748	$ 682	$ 849	$ 667	$ 268	$ 375	$ 383	$ 447	$ 345	$ 1,062	$ 385	$ 989	$ 767	$ 1,326	$ 773	$ 1,453	$ 3,815	$ 3,073	$ 2,220	$ 4,041	$ 52	$ 258	$ 120	$ 55	$ 5,287	$ 8,287	$ 5,364	$ 8,318	$ 4,514	$ 4,278	$ 4,931	$ 4,682	$ 2,203	$ 2,691	$ 1,942	$ 2,569	$ 2,428	$ 2,322	$ 2,452	$ 2,245	$ 298	$ 691	$ 181	$ 726	$ 140	$ (370)		$ (562)	$ (1,474)	$ (1,077)	$ (1,448)	$ (1,737)	$ (637)	$ (859)	$ (771)	$ (934)	$ (156)	$ 228	$ (342)	$ 1,728
Net realized/unrealized gains (losses) included in principal transactions, assets																										(150)	32	(163)	65	459	(183)	991	246	252	41	526	43	27	(17)	76	33	187	61	358	80	38	(3)	92	(70)			18	20	19	17	(4)	1	(2)	4	74	(110)	(30)	9	(33)	(75)	4	(71)	144	(113)	368	222	8	53	106	22	1,035	(339)	1,149	(1,070)																																																																339	359	312	142	213	(93)	311	80	169	(275)	261	199	357	(113)	411	(39)	(43)	(217)	(146)	(1,452)
Net realized/unrealized gains (losses) included in locations other than principal transactions, assets																																																																																135	7	241	258	13	(13)	25	(4)	(1)	(13)	2	(4)	14		23									15	14	(2)	13	(5)	13	(4)	16	(4)	(1)	(3)	(5)	(5)	4	(3)	49	12	7	50	10					109	(17)	178	179	(3)	(25)	(78)	(62)	227	(480)	417	(293)	(30)	91	6	98
Transfers into Level 3, assets																												598	25	1,181	1,253	2,042	2,273	630	644	1,209	1,089	345	159	737	538	219	430	317	460	66	55	155	91							47	10	53	12	62	21	138	348	25	1	48	19	48	148	86	165	369	429	508	640	354	(261)	872	(130)	558	125	3,572	125	267		1,960		264		1,897				60		3		3							7		83	80	105	80	191	45	291	45	17		17				1,192										353	917	353	917							1	8	235	(219)	749	123	20	(77)	30	(82)	(2)	(39)	(24)	(36)	(1)		7	(5)	102	74	110	(130)
Transfers out of Level 3, assets																										(39)	(115)	(1,318)	(377)	(1,285)	(2,371)	(2,474)	(3,468)	(487)	(418)	(1,101)	(833)	(303)	(218)	(705)	(345)	(36)	(120)	(212)	(300)	(148)	(80)	(184)	(188)				(7)		(7)	(25)	(477)	(61)	(740)	(83)	(266)	(100)	(391)	(96)	(4)	(159)	(13)	(23)	(25)	(55)	(61)	(571)	(1,174)	(998)	(1,423)	511	(87)	284	280	(4,206)	(1,872)	(5,950)	(2,654)	(2,391)	(886)	(3,627)	(1,533)	(2,319)	(880)	(3,350)	(1,521)	(60)		(265)	(6)	(12)	(6)	(12)	(6)			(75)		(151)	(117)	(151)	(27)	(139)	(201)	(156)	(104)	(696)	(116)	(696)					(1,684)		(1,684)	(43)		(205)										(25)						(30)		(31)	275	(102)	108	(119)	13	54	3	46	265	(69)	346	367	7	36	5	45	(49)	(6)	(178)	(59)
Purchases, assets																										17		17		5,158	2,754	9,289	9,752	1,939	801	3,013	1,887	689	72	969	255	1,171	625	1,898	1,317	79	104	146	315	13	13	56	6	75	28	52	132	117	842	811	260	1,379	1,756	62	126	140	204	1,449	1,009	3,032	3,660	789	407	1,533	1,362	141	176	301	794	1,044	2,095	2,590	3,332	11	1,674	599	2,565	(1)	1,360	470	2,245		309	117	309	12	5	12	11				126	126	207	158	159	112	289	201	2	42	16	129			1		233	12	925	12					513	129	553	267	(36)	21	59	107				2	78	1	216	2	52	17	143	216	6	59	15	188	67	69	116	203	12	28	15	73	4	3	12	114
Issuance, assets																														29	14	55	45	29	14	55	45	29	14	55	45																																																																																										6	515	13	515	205	79	377	221	50	353	340	629
Sales, assets																														(3,728)	(3,351)	(8,469)	(8,973)	(1,173)	(794)	(2,913)	(1,882)	(339)	(189)	(707)	(414)	(715)	(397)	(1,221)	(1,118)	(119)	(208)	(985)	(350)		(3)	(42)	(19)	(48)	(67)	(58)	(166)	(178)	(306)	(376)	(804)	(819)	(1,399)	(47)	(22)	(107)	(142)	(1,552)	(1,239)	(3,408)	(4,293)	(480)	(307)	(996)	(881)	(81)	(270)	(171)	(759)	(373)	(1,837)	(687)	(2,191)	(140)		(140)						(140)		(140)						(2)	(3)		(80)	(191)	(135)	(207)	(84)	(110)	(151)	(190)	(4)	(29)	(147)	(36)		(2)	(9)	(174)		(43)	(17)	(50)	(1)	(2)	(64)		(62)	(1,462)	(83)	(1,470)	57	(87)	(6)	(95)			(1)	(5)	(2,005)	(4)	(2,010)	(42)	(67)	(10)	(82)	(139)	(1)	(90)	(8)	(197)	5	(160)	(56)	(335)	(18)	(10)	(25)	(78)				(10)
Settlements, assets																														(874)	(1,472)	(1,395)	(2,335)	(22)	(42)	(70)	(81)	(22)	(41)	(46)	(78)		(1)	(7)	(3)			(17)												(536)	(675)	(910)	(1,374)				(24)	(217)	(600)	(217)	(659)	(99)	(155)	(198)	(197)	(32)	79	44	(425)	(1,325)	(1,089)	(1,835)	(2,438)	(49)		(57)		(49)		(57)													(125)		(125)		(27)	(2)	(54)	(69)	(22)	(2)	(22)	(5)		(148)		(148)	(618)	(278)	(928)	(1,199)			(1)		(484)	(659)	(649)	(1,016)	(570)	(882)	(951)	(1,302)	(111)	(173)	(211)	(377)	(276)	(358)	(760)	(534)	(49)	(117)	(328)	(330)	(24)		16	10	(122)	(36)	(287)	(248)	62	16	140	36	101	216	503	107
Balance at end of period, asset																										4,177	4,414	4,177	4,414	13,862	13,332	13,862	13,332	4,968	3,256	4,968	3,256	1,704	895	1,704	895	2,938	1,945	2,938	1,945	326	416	326	416	13	13	241	223	241	223	240	333	240	333	1,688	2,189	1,688	2,189	190	217	190	217	4,259	4,835	4,259	4,835	2,276	2,266	2,276	2,266	99	(2,089)	99	(2,089)	9,838	13,229	9,838	13,229	423	1,715	423	1,715	420	1,399	420	1,399		311		311	3	5	3	5	9	9		684	480	684	480	367	329	367	329	404	421	404	421	779	1,180	779	1,180	1,758	2,771	1,758	2,771	51	51	55	55	5,363	6,278	5,363	6,278	4,321	4,737	4,321	4,737	2,524	2,117	2,524	2,117	245	2,375	245	2,375	1,083	619	1,083	619	367	(517)	367	(517)	(1,092)	(1,587)	(1,092)	(1,587)	(218)	(902)	(218)	(902)	(41)	298	(41)	298
Unrealized gains (losses) still held, assets																										365	33	123	65	70	(148)	48	93	42	(52)	150	(19)	(9)	(42)	43	(17)	44	(8)	99	2	7	(2)	8				(6)	8	(6)	(2)	(2)	(1)	(2)	(1)	65	(70)	(406)	83	(24)	(10)	286	(14)	(2)	(139)	13	(76)	(3)	116	13	118	516	(491)	1,129	(2,255)	59	(170)	168	58	5	(10)	2	(10)	5	(9)	2	(8)		(1)		(2)								13	(7)	(6)	(9)			(6)	1	1	5	3	8	(38)	2	(38)	(6)	6	1	6	1					72	(161)	207	73		43	178	54	228	(479)	191	(295)	(35)	86	194	99	434	167	983	(118)	(64)	24	(151)	71	(389)	(260)	(589)	(476)	528	(97)	669	(308)	7	(325)	217	(1,424)
Threshold tenor of repo curves to classify structured reverse repos as level 3																									5 years
Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation
Balance at beginning of period, liability	834	458	786	431	1,053	1,025	841	1,061	335	177	365	412	53	423	112	499	6,847	6,519	6,726	6,904	16	2	24	3
Net realized/unrealized gains (losses) included in principal transactions, liabilities					33	(92)	60	(65)	(8)	12	11	(60)	(16)		26	(56)	380	219	371	141
Net realized/unrealized gains (losses) included in locations other than principal transactions, liabilities	(51)	(15)	(67)	(20)													36	52	69	81	(186)	(1)	(185)	(2)
Transfers into Level 3, liabilities		130	22	213			201		4	1	24	5		3		3	730	190	1,365	349	3		5
Transfers out of Level 3, liabilities					(15)		(15)		(6)	(24)	(11)	(31)	(4)	(2)	(4)	(11)	(549)	(490)	(1,014)	(906)			(2)
Purchases, liability																					(1)	(1)	(3)	(2)
Issuance, liability	38	172	63	180									290	69	291	195	621	888	905	1,175	88	1	90	1
Sales, liability					2	4	40	4	130	69	176	140							(1)
Settlements, liability	(92)	(77)	(107)	(146)		(76)		(85)	(21)	(63)	(93)	(438)	(20)	(126)	(38)	(375)	(422)	(884)	(730)	(1,348)	(197)	(1)	(204)	(2)
Balance at end of period, liability	831	698	831	698	1,007	1,045	1,007	1,045	450	148	450	148	335	367	335	367	6,811	5,952	6,811	5,952	95	2	95	2
Unrealized gains (losses) still held, liabilities	$ (23)	$ (109)	$ (164)	$ (329)	$ 29	$ 118	$ 41	$ 118	$ (40)	$ 1	$ 88	$ (53)	$ (45)	$ 40	$ (44)	$ 38	$ (464)	$ (174)	$ (907)	$ (332)	$ (196)	$ (1)	$ (198)