Securities (Summary Of Assumptions Utilized In Valuation Of Other-Than-Temporarily Impaired Residential Mortgage-Backed Securities Issued By Nongovernment-Sponsored Entities) (Details)	9 Months Ended
	Sep. 30, 2012
Weighted Average [Member]
Summary Of Assumptions Utilized In Valuation Of Other-Than-Temporarily Impaired Residential Mortgage-Backed Securities Issued By Nongovernment-Sponsored Entities [Line Items]
Constant voluntary prepayment rates	12.20%
Constant default rates	4.90%
Loss severities	45.50%
Minimum [Member]
Summary Of Assumptions Utilized In Valuation Of Other-Than-Temporarily Impaired Residential Mortgage-Backed Securities Issued By Nongovernment-Sponsored Entities [Line Items]
Constant voluntary prepayment rates	10.10%
Constant default rates	4.60%
Loss severities	40.00%
Maximum [Member]
Summary Of Assumptions Utilized In Valuation Of Other-Than-Temporarily Impaired Residential Mortgage-Backed Securities Issued By Nongovernment-Sponsored Entities [Line Items]
Constant voluntary prepayment rates	14.10%
Constant default rates	5.20%
Loss severities	52.00%