Fair Value Measurements (Details 1) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	$ 818	$ 945	$ 900
Total Derivative assets	818	945	900
Recurring [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	679
Commercial loans
Trading account assets	679
Securities available for sale	13,205	16,012
Total other investments	785	760
Derivative assets	2,200	2,397
Netting adjustments	(1,382)	(1,452)
Total Derivative assets	818	945
Accrued income and other assets	136	112
Total assets on a recurring basis at fair value	15,961	18,688
LIABILITIES MEASURED ON A RECURRING BASIS
Securities sold under repurchase agreements	481	292
Bank notes and other short-term borrowings, Short positions	363	337
Derivative liabilities	1,643	2,004
Netting adjustments	(880)	(978)
Total derivative liabilities	763	1,026
Accrued expense and other liabilities	4	45
Total liabilities on a recurring basis at fair value	1,611	1,700
Recurring [Member] | Short-term investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities purchased under resale agreements	338	236
Recurring [Member] | U.S. Treasury, agencies and corporations [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	438	353
Recurring [Member] | States and political subdivisions [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	84	81
Securities available for sale	56	63
Recurring [Member] | Collateralized mortgage obligations [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	16	19
Securities available for sale	12,477	15,162
Recurring [Member] | Other mortgage-backed securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	101	62
Securities available for sale	652	778
Recurring [Member] | Other securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	40	108
Securities available for sale	20	9
Recurring [Member] | Total trading account securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities		623
Trading account assets		623
Recurring [Member] | Principal Direct Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	242	236
Recurring [Member] | Principal Indirect Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	482	473
Recurring [Member] | Principal Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	724	709
Recurring [Member] | Equity and Mezzanine Direct Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	18	15
Recurring [Member] | Equity and Mezzanine Indirect Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	43	36
Recurring [Member] | Private Equity and Mezzanine Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	61	51
Recurring [Member] | Interest rate [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	1,859	1,953
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1,310	1,398
Recurring [Member] | Foreign exchange [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	107	151
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	105	288
Recurring [Member] | Energy and commodity [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	209	253
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	204	253
Recurring [Member] | Credit [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	25	37
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	24	62
Recurring [Member] | Equity [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets		3
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities		3
Recurring [Member] | Level 1 [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	3
Commercial loans
Trading account assets	3
Securities available for sale	20	9
Total other investments	11	11
Derivative assets	81	86
Total Derivative assets	81	86
Accrued income and other assets	2	7
Total assets on a recurring basis at fair value	117	192
LIABILITIES MEASURED ON A RECURRING BASIS
Bank notes and other short-term borrowings, Short positions	3
Derivative liabilities	81	79
Total derivative liabilities	81	79
Accrued expense and other liabilities		23
Total liabilities on a recurring basis at fair value	84	102
Recurring [Member] | Level 1 [Member] | Other securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	3	79
Securities available for sale	20	9
Recurring [Member] | Level 1 [Member] | Total trading account securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities		79
Trading account assets		79
Recurring [Member] | Level 1 [Member] | Principal Direct Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	11	11
Recurring [Member] | Level 1 [Member] | Principal Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	11	11
Recurring [Member] | Level 1 [Member] | Foreign exchange [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	81	86
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	81	79
Recurring [Member] | Level 1 [Member] | Equity [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities
Recurring [Member] | Level 2 [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	618
Commercial loans
Trading account assets	618
Securities available for sale	13,185	16,003
Derivative assets	2,078	2,266
Total Derivative assets	2,078	2,266
Accrued income and other assets	134	105
Total assets on a recurring basis at fair value	16,353	19,119
LIABILITIES MEASURED ON A RECURRING BASIS
Securities sold under repurchase agreements	481	292
Bank notes and other short-term borrowings, Short positions	360	337
Derivative liabilities	1,560	1,896
Total derivative liabilities	1,560	1,896
Accrued expense and other liabilities	4	22
Total liabilities on a recurring basis at fair value	2,405	2,547
Recurring [Member] | Level 2 [Member] | Short-term investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities purchased under resale agreements	338	236
Recurring [Member] | Level 2 [Member] | U.S. Treasury, agencies and corporations [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	438	353
Recurring [Member] | Level 2 [Member] | States and political subdivisions [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	27	81
Securities available for sale	56	63
Recurring [Member] | Level 2 [Member] | Collateralized mortgage obligations [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	16	19
Securities available for sale	12,477	15,162
Recurring [Member] | Level 2 [Member] | Other mortgage-backed securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	100	27
Securities available for sale	652	778
Recurring [Member] | Level 2 [Member] | Other securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	37	29
Recurring [Member] | Level 2 [Member] | Total trading account securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities		509
Trading account assets		509
Recurring [Member] | Level 2 [Member] | Interest rate [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	1,824	1,915
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1,310	1,398
Recurring [Member] | Level 2 [Member] | Foreign exchange [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	26	65
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	24	209
Recurring [Member] | Level 2 [Member] | Energy and commodity [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	209	253
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	203	252
Recurring [Member] | Level 2 [Member] | Credit [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	19	30
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	23	34
Recurring [Member] | Level 2 [Member] | Equity [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0	3
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities		3
Recurring [Member] | Level 3 [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	58
Commercial loans
Trading account assets	58
Total other investments	774	749
Derivative assets	41	45
Total Derivative assets	41	45
Total assets on a recurring basis at fair value	873	829
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	2	29
Total derivative liabilities	2	29
Total liabilities on a recurring basis at fair value	2	29
Recurring [Member] | Level 3 [Member] | States and political subdivisions [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	57
Recurring [Member] | Level 3 [Member] | Other mortgage-backed securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	1	35
Recurring [Member] | Level 3 [Member] | Total trading account securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities		35
Trading account assets		35
Recurring [Member] | Level 3 [Member] | Principal Direct Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	231	225
Recurring [Member] | Level 3 [Member] | Principal Indirect Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	482	473
Recurring [Member] | Level 3 [Member] | Principal Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	713	698
Recurring [Member] | Level 3 [Member] | Equity and Mezzanine Direct Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	18	15
Recurring [Member] | Level 3 [Member] | Equity and Mezzanine Indirect Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	43	36
Recurring [Member] | Level 3 [Member] | Private Equity and Mezzanine Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	61	51
Recurring [Member] | Level 3 [Member] | Interest rate [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	35	38
Recurring [Member] | Level 3 [Member] | Energy and commodity [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1	1
Recurring [Member] | Level 3 [Member] | Credit [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	6	7
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities	1	28
Recurring [Member] | Level 3 [Member] | Equity [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets	0
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities