Fair Value Fair Value (Carrying Value and Estimated Fair Value of Financial Instruments) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2010
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	$ 6,432	$ 2,193	$ 9,487	$ 3,311
Interest-bearing deposits with banks	31,583	58,886
Securities purchased under resale agreements	8,264	7,045
Investment securities held to maturity, Reported Amount	8,360	9,321
Deposits, Noninterest-bearing	40,963	59,229
Deposits, Interest-bearing - U.S.	11,107	7,148
Deposits, Interest-bearing - Non-U.S.	94,219	90,910
Securities sold under repurchase agreements	7,933	8,572
Federal funds purchased	169	656
Other short-term borrowings	5,181	4,766
Long-term debt	6,418	8,131
Reported Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	6,432
Interest-bearing deposits with banks	31,583
Securities purchased under resale agreements	8,264
Investment securities held to maturity, Reported Amount	8,360
Loans (excluding Leases)	12,845	8,777
Portion at Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	6,432
Interest-bearing deposits with banks	31,583
Securities purchased under resale agreements	8,264
Investment securities held to maturity, Reported Amount	8,622
Loans (excluding Leases)	12,858
Deposits, Noninterest-bearing	40,963
Deposits, Interest-bearing - U.S.	11,107
Deposits, Interest-bearing - Non-U.S.	94,219
Securities sold under repurchase agreements	7,933
Federal funds purchased	169
Other short-term borrowings	5,181
Long-term debt	6,700
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	6,432
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	31,583
Securities purchased under resale agreements	8,264
Investment securities held to maturity, Reported Amount	8,622
Loans (excluding Leases)	11,878
Deposits, Noninterest-bearing	40,963
Deposits, Interest-bearing - U.S.	11,107
Deposits, Interest-bearing - Non-U.S.	94,219
Securities sold under repurchase agreements	7,933
Federal funds purchased	169
Other short-term borrowings	5,181
Long-term debt	5,808
Fair Value, Inputs, Level 3 [Member] | Portion at Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans (excluding Leases)	980
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	$ 892