Investment Securities (Credit Ratings In State And Municipal Bond Portfolio) (Details)	Dec. 31, 2011
Percentage of State and Municipal Bond Portfolio, by credit rating	100.00%
Moody's, Aaa Rating [Member]
Percentage of State and Municipal Bond Portfolio, by credit rating	14.90%
Moody's, Aa Rating [Member]
Percentage of State and Municipal Bond Portfolio, by credit rating	67.20%
Moody's, A Rating [Member]
Percentage of State and Municipal Bond Portfolio, by credit rating	14.90%
Moody's, Baa Rating [Member]
Percentage of State and Municipal Bond Portfolio, by credit rating	1.30%
Moody's, Not Rated [Member]
Percentage of State and Municipal Bond Portfolio, by credit rating	1.70%