Fair Value Fair Value (Carrying Value and Estimated Fair Value of Financial Instruments) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Due from Banks	$ 1,383	$ 2,193	$ 2,637	$ 3,311
Interest-bearing deposits with banks	26,709	58,886
Securities purchased under resale agreements	7,895	7,045
Investment securities held to maturity, Reported Amount	8,668	9,321
Deposits, Noninterest-bearing	37,201	59,229
Deposits, Interest-bearing - U.S.	2,731	7,148
Deposits, Interest-bearing - Non-U.S.	90,248	90,910
Securities sold under repurchase agreements	7,836	8,572
Federal funds purchased	222	656
Other short-term borrowings	4,759	4,766
Long-term debt	8,117	8,131
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Due from Banks	1,383
Interest-bearing deposits with banks	26,709
Securities purchased under resale agreements	7,895
Investment securities held to maturity, Reported Amount	8,668
Loans (excluding Leases)	11,011
Deposits, Noninterest-bearing	37,201
Deposits, Interest-bearing - U.S.	2,731
Deposits, Interest-bearing - Non-U.S.	90,248
Securities sold under repurchase agreements	7,836
Federal funds purchased	222
Other short-term borrowings	4,759
Long-term debt	8,117
Portion at Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Due from Banks	1,383
Interest-bearing deposits with banks	26,709
Securities purchased under resale agreements	7,895
Investment securities held to maturity, Reported Amount	8,842
Loans (excluding Leases)	11,000
Deposits, Noninterest-bearing	37,201
Deposits, Interest-bearing - U.S.	2,731
Deposits, Interest-bearing - Non-U.S.	90,248
Securities sold under repurchase agreements	7,836
Federal funds purchased	222
Other short-term borrowings	4,759
Long-term debt	8,301
Fair Value, Inputs, Level 1 [Member] | Portion at Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Due from Banks	1,383
Interest-bearing deposits with banks
Securities purchased under resale agreements	0
Investment securities held to maturity, Reported Amount	0
Loans (excluding Leases)	0
Deposits, Noninterest-bearing	0
Deposits, Interest-bearing - U.S.	0
Deposits, Interest-bearing - Non-U.S.	0
Securities sold under repurchase agreements	0
Federal funds purchased	0
Other short-term borrowings	0
Long-term debt	0
Fair Value, Inputs, Level 2 [Member] | Portion at Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest-bearing deposits with banks	26,709
Securities purchased under resale agreements	7,895
Investment securities held to maturity, Reported Amount	8,806
Loans (excluding Leases)	9,723
Deposits, Noninterest-bearing	37,201
Deposits, Interest-bearing - U.S.	2,731
Deposits, Interest-bearing - Non-U.S.	90,248
Securities sold under repurchase agreements	7,836
Federal funds purchased	222
Other short-term borrowings	4,759
Fair Value, Inputs, Level 3 [Member] | Portion at Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities held to maturity, Reported Amount	36
Loans (excluding Leases)	1,277
Long-term debt	$ 8,301