Fair Value (Carrying Value and Estimated Fair Value of Financial Instruments) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Financial Assets:
Cash and due from banks	$ 3,220	$ 2,590	$ 2,193	$ 3,311
Interest-bearing deposits with banks	64,257	50,763
Securities purchased under resale agreements	6,230	5,016
Investment securities held to maturity	17,740	11,379
Financial Liabilities:
Noninterest-bearing	65,614	44,445
Interest-bearing—U.S.	13,392	19,201
Interest-bearing—non-U.S.	103,262	100,535
Securities sold under repurchase agreements	7,953	8,006
Federal funds purchased	19	399
Other short-term borrowings	3,780	4,502
Long-term debt	9,699	7,429
Reported Amount
Financial Assets:
Cash and due from banks	3,220	2,590
Interest-bearing deposits with banks	64,257	50,763
Securities purchased under resale agreements	6,230	5,016
Investment securities held to maturity	17,740	11,379
Net loans (excluding leases)	12,363	11,121
Financial Liabilities:
Noninterest-bearing	65,614	44,445
Interest-bearing—U.S.	13,392	19,201
Interest-bearing—non-U.S.	103,262	100,535
Securities sold under repurchase agreements	7,953	8,006
Federal funds purchased	19	399
Other short-term borrowings	3,780	4,502
Long-term debt	9,699	7,429
Estimated Fair Value
Financial Assets:
Cash and due from banks	3,220	2,590
Interest-bearing deposits with banks	64,257	50,763
Securities purchased under resale agreements	6,230	5,016
Investment securities held to maturity	17,560	11,661
Net loans (excluding leases)	12,355	11,166
Financial Liabilities:
Noninterest-bearing	65,614	44,445
Interest-bearing—U.S.	13,392	19,201
Interest-bearing—non-U.S.	103,262	100,535
Securities sold under repurchase agreements	7,953	8,006
Federal funds purchased	19	399
Other short-term borrowings	3,780	4,502
Long-term debt	10,023	7,780
Quoted Market Prices in Active Markets (Level 1) | Estimated Fair Value
Financial Assets:
Cash and due from banks	3,220	2,590
Interest-bearing deposits with banks	0	0
Securities purchased under resale agreements	0	0
Investment securities held to maturity	0	0
Net loans (excluding leases)	0	0
Financial Liabilities:
Noninterest-bearing	0	0
Interest-bearing—U.S.	0	0
Interest-bearing—non-U.S.	0	0
Securities sold under repurchase agreements	0	0
Federal funds purchased	0	0
Other short-term borrowings	0	0
Long-term debt	0	0
Pricing Methods with Significant Observable Market Inputs (Level 2) | Estimated Fair Value
Financial Assets:
Cash and due from banks	0	0
Interest-bearing deposits with banks	64,257	50,763
Securities purchased under resale agreements	6,230	5,016
Investment securities held to maturity	17,560	11,661
Net loans (excluding leases)	11,908	10,316
Financial Liabilities:
Noninterest-bearing	65,614	44,445
Interest-bearing—U.S.	13,392	19,201
Interest-bearing—non-U.S.	103,262	100,535
Securities sold under repurchase agreements	7,953	8,006
Federal funds purchased	19	399
Other short-term borrowings	3,780	4,502
Long-term debt	9,056	6,871
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Estimated Fair Value
Financial Assets:
Cash and due from banks	0	0
Interest-bearing deposits with banks	0	0
Securities purchased under resale agreements	0	0
Investment securities held to maturity	0	0
Net loans (excluding leases)	447	850
Financial Liabilities:
Noninterest-bearing	0	0
Interest-bearing—U.S.	0	0
Interest-bearing—non-U.S.	0	0
Securities sold under repurchase agreements	0	0
Federal funds purchased	0	0
Other short-term borrowings	0	0
Long-term debt	$ 967	$ 909