Fair Value Fair Value (Carrying Value and Estimated Fair Value of Financial Instruments) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	$ 2,590	$ 2,193	$ 3,311	$ 2,641
Interest-bearing deposits with banks	50,763	58,886
Securities purchased under resale agreements	5,016	7,045
Investment securities held to maturity, Reported Amount	11,379	9,321
Deposits, Noninterest-bearing	44,445	59,229
Deposits, Interest-bearing - U.S.	19,201	7,148
Deposits, Interest-bearing - Non-U.S.	100,535	90,910
Securities sold under repurchase agreements	8,006	8,572
Federal funds purchased	399	656
Other short-term borrowings	4,502	4,766
Long-term debt	7,429	8,131
Reported Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	2,590
Interest-bearing deposits with banks	50,763
Securities purchased under resale agreements	5,016
Investment securities held to maturity, Reported Amount	11,379
Loans (excluding Leases)	11,121	8,777
Deposits, Noninterest-bearing	44,445
Deposits, Interest-bearing - U.S.	19,201
Deposits, Interest-bearing - Non-U.S.	100,535
Securities sold under repurchase agreements	8,006
Federal funds purchased	399
Other short-term borrowings	4,502
Long-term debt	7,429
Portion at Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	2,590
Interest-bearing deposits with banks	50,763
Securities purchased under resale agreements	5,016
Investment securities held to maturity, Reported Amount	11,661
Loans (excluding Leases)	11,166
Deposits, Noninterest-bearing	44,445
Deposits, Interest-bearing - U.S.	19,201
Deposits, Interest-bearing - Non-U.S.	100,535
Securities sold under repurchase agreements	8,006
Federal funds purchased	399
Other short-term borrowings	4,502
Long-term debt	6,779
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	2,590
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]
Cash and due from banks	0
Interest-bearing deposits with banks	50,763
Securities purchased under resale agreements	5,016
Investment securities held to maturity, Reported Amount	11,661
Loans (excluding Leases)	10,276
Deposits, Noninterest-bearing	44,445
Deposits, Interest-bearing - U.S.	19,201
Deposits, Interest-bearing - Non-U.S.	100,535
Securities sold under repurchase agreements	8,006
Federal funds purchased	399
Other short-term borrowings	4,502
Long-term debt	5,871
Fair Value, Inputs, Level 3 [Member] | Portion at Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	0
Interest-bearing deposits with banks	0
Securities purchased under resale agreements	0
Investment securities held to maturity, Reported Amount	0
Loans (excluding Leases)	890
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	$ 909