Contingent Liabilities - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008	Dec. 31, 2007	Mar. 31, 2012
Commitments and Contingencies Disclosure [Line Items]
Standby letters of credit outstanding		$ 4,300,000,000					$ 4,500,000,000
Standby letters of credit, unamortized fees		43,800,000					50,100,000
Minimum securities lending related collateral percentage		100.00%					100.00%
Possible loss in future periods in excess of accrual							39,000,000
Gain on redemption of Visa common stock					167,900,000
Remaining Visa shares held by Northern Trust, original cost basis					0
Visa indemnified litigation benefit (charges) recorded	10,100,000	23,100,000	33,000,000	17,800,000	76,100,000	(150,000,000)
Fair value of contingent consideration		56,800,000					58,600,000
Indemnification Agreement
Commitments and Contingencies Disclosure [Line Items]
Collateralized securities loaned, subject to indemnification		74,400,000,000					74,300,000,000
Credit loss liability		$ 0					$ 0