Securities (Summary Of Assumptions Utilized In Valuation Of Other-Than-Temporarily Impaired Residential Mortgage-Backed Securities Issued By Nongovernment-Sponsored Entities) (Details)	12 Months Ended
	Dec. 31, 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 prepayment rates	11.30%
Constant default rates	5.30%
Loss severities	48.20%
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 prepayment rates	7.20%
Constant default rates	5.10%
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 prepayment rates	13.10%
Constant default rates	6.90%
Loss severities	52.00%