Securities (Summary Of Assumptions Utilized In Valuation Of Other-Than-Temporarily Impaired Residential Mortgage-Backed Securities Issued By Nongovernment-Sponsored Entities) (Details)	3 Months Ended
	Mar. 31, 2013
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	14.00%
Constant default rates	5.60%
Loss severities	40.00%
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	14.00%
Constant default rates	5.60%
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	14.00%
Constant default rates	5.60%
Loss severities	40.00%