Securities (Schedule of Contractual Maturities of Investment Securities Available for Sale) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Available-for-sale Securities [Abstract]
Due within one year, Amortized Cost	$ 25,062
Due after one year through five years, Amortized Cost	127,971
Due after five years through ten years, Amortized Cost	209,031
Due after ten years, Amortized Cost	603,971
Total investment securities available-for-sale, Amortized Cost	969,359
Due within one year, Fair Value	25,440
Due after one year through five years, Fair Value	131,704
Due after five years through ten years, Fair Value	215,390
Due after ten years, Fair Value	625,739
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis	3,324
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value	3,392
Total investment securities available-for-sale, Fair Value	$ 1,001,665