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Securities (Schedule Of Amortized Cost Of Equity Securities Related To Federal Reserve Bank Stock And Federal Home Loan Bank Stock) (Detail) (USD $)
In Millions, unless otherwise specified
Jun. 30, 2012
Dec. 31, 2011
Contractual Maturity Of Securities Available For Sale And Securities Held To Maturity [Line Items]    
Federal Reserve Bank $ 480 $ 481
Federal Home Loan Bank $ 135 $ 219