Fair Value Fair Value (Carrying Value and Estimated Fair Value of Financial Instruments) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	$ 6,088	$ 2,193	$ 4,572	$ 3,311
Interest-bearing deposits with banks	31,145	58,886
Securities purchased under resale agreements	8,144	7,045
Investment securities held to maturity, Reported Amount	7,807	9,321
Deposits, Noninterest-bearing	41,194	59,229
Deposits, Interest-bearing - U.S.	11,209	7,148
Deposits, Interest-bearing - Non-U.S.	91,368	90,910
Securities sold under repurchase agreements	8,893	8,572
Federal funds purchased	671	656
Other short-term borrowings	4,714	4,766
Long-term debt	6,392	8,131
Reported Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	6,088
Interest-bearing deposits with banks	31,145
Securities purchased under resale agreements	8,144
Investment securities held to maturity, Reported Amount	7,807
Loans (excluding Leases)	11,139	8,777
Deposits, Noninterest-bearing	41,194
Deposits, Interest-bearing - U.S.	11,209
Deposits, Interest-bearing - Non-U.S.	91,368
Securities sold under repurchase agreements	8,893
Federal funds purchased	671
Other short-term borrowings	4,714
Long-term debt	6,392
Portion at Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	6,088
Interest-bearing deposits with banks	31,145
Securities purchased under resale agreements	8,144
Investment securities held to maturity, Reported Amount	7,934
Loans (excluding Leases)	11,145
Deposits, Noninterest-bearing	41,194
Deposits, Interest-bearing - U.S.	11,209
Deposits, Interest-bearing - Non-U.S.	91,368
Securities sold under repurchase agreements	8,893
Federal funds purchased	671
Other short-term borrowings	4,714
Long-term debt	6,636
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	6,088
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	31,145
Securities purchased under resale agreements	8,144
Investment securities held to maturity, Reported Amount	7,898
Loans (excluding Leases)	10,044
Deposits, Noninterest-bearing	41,194
Deposits, Interest-bearing - U.S.	11,209
Deposits, Interest-bearing - Non-U.S.	91,368
Securities sold under repurchase agreements	8,893
Federal funds purchased	671
Other short-term borrowings	4,714
Long-term debt	5,746
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)	1,101
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	$ 890