Fair Value Measurement - Carrying Value and Estimated Fair Value (Details 7) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2010	Mar. 31, 2010
Financial assets
Cash and due from banks	$ 55,383,000,000	$ 23,469,000,000	$ 59,602,000,000	$ 27,567,000,000
Assets for which fair value approximates carrying value	55,383,000,000	23,469,000,000	59,602,000,000	27,567,000,000
Deposits with banks	115,028,000,000		85,279,000,000
Federal funds sold and securities purchased under resale agreements (included $24.2 and $20.3 at fair value)	240,484,000,000		235,314,000,000
Mortgage servicing rights at fair value	8,039,000,000	13,093,000,000	7,223,000,000		13,649,000,000
Trading assets and liabilities average balances Abstract
Trading assets - debt and equity instruments	355,335,000,000	417,463,000,000
Trading assets - derivative receivables	90,446,000,000	85,437,000,000
Trading liabilities - debt and equity instruments	68,984,000,000	82,919,000,000
Trading liabilities - derivative payables	76,069,000,000	71,288,000,000
Fair Value, Measurements, Recurring [Member]
Financial assets
Trading assets	455,633,000,000		443,963,000,000
Mortgage servicing rights at fair value	8,039,000,000		7,223,000,000
Financial liabilities
Trading liabilities	146,296,000,000		141,695,000,000
Fair value | Fair Value, Measurements, Recurring [Member]
Financial assets
Federal funds sold and securities purchased under resale agreements (included $24.2 and $20.3 at fair value)	26,259,000,000		24,891,000,000
Loans, at fair value	2,288,000,000		2,097,000,000
Carrying value
Financial assets
Cash and due from banks	55,400,000,000		59,600,000,000
Assets for which fair value approximates carrying value	55,400,000,000		59,600,000,000
Deposits with banks	115,000,000,000		85,300,000,000
Accrued interest and accounts receivable	64,800,000,000		61,500,000,000
Federal funds sold and securities purchased under resale agreements (included $24.2 and $20.3 at fair value)	214,200,000,000		210,400,000,000
Securities borrowed	123,100,000,000		127,200,000,000
Loans, at fair value	692,800,000,000		694,000,000,000
Other	47,700,000,000		49,800,000,000
Financial liabilities
Deposits	1,123,200,000,000		1,122,900,000,000
Federal funds purchased and securities loaned or sold under repurchase agreements (included $9.5 and $4.1 at fair value)	237,200,000,000		204,000,000,000
Commercial paper	50,600,000,000		51,600,000,000
Other borrowed funds	17,100,000,000		12,300,000,000
Accounts payable and other liabilities	168,600,000,000		166,900,000,000
Beneficial interests issued by consolidated VIEs, at fair value	66,700,000,000		64,700,000,000
Long-term debt and junior subordinated deferrable interest debentures	220,400,000,000		222,100,000,000
Wholesale lending related commitments	700,000,000		700,000,000
Estimate of Fair Value
Financial assets
Cash and due from banks			59,600,000,000
Assets for which fair value approximates carrying value			59,600,000,000
Deposits with banks			85,300,000,000
Accrued interest and accounts receivable			61,500,000,000
Federal funds sold and securities purchased under resale agreements (included $24.2 and $20.3 at fair value)			210,400,000,000
Securities borrowed			127,200,000,000
Loans, at fair value			693,700,000,000
Other			50,300,000,000
Financial liabilities
Deposits			1,123,400,000,000
Federal funds purchased and securities loaned or sold under repurchase agreements (included $9.5 and $4.1 at fair value)			204,000,000,000
Commercial paper			51,600,000,000
Other borrowed funds			12,300,000,000
Accounts payable and other liabilities			166,800,000,000
Beneficial interests issued by consolidated VIEs, at fair value			64,900,000,000
Long-term debt and junior subordinated deferrable interest debentures			219,500,000,000
Wholesale lending related commitments			3,400,000,000
Estimate of fair value, predominantly level 3 inputs
Financial assets
Loans, at fair value	692,000,000,000
Financial liabilities
Wholesale lending related commitments	1,900,000,000
Estimate of fair value, predominantly level 2 inputs
Financial assets
Accrued interest and accounts receivable	64,800,000,000
Federal funds sold and securities purchased under resale agreements (included $24.2 and $20.3 at fair value)	214,200,000,000
Securities borrowed	123,100,000,000
Other	48,200,000,000
Financial liabilities
Deposits	1,123,800,000,000
Federal funds purchased and securities loaned or sold under repurchase agreements (included $9.5 and $4.1 at fair value)	237,200,000,000
Commercial paper	50,600,000,000
Other borrowed funds	17,100,000,000
Accounts payable and other liabilities	168,500,000,000
Beneficial interests issued by consolidated VIEs, at fair value	67,000,000,000
Long-term debt and junior subordinated deferrable interest debentures	222,200,000,000
Estimate of fair value, predominantly level 1 inputs
Financial assets
Cash and due from banks	55,400,000,000
Assets for which fair value approximates carrying value	55,400,000,000
Deposits with banks	$ 115,000,000,000