Securities (Schedule of Contractual Maturities of Investment Securities Available for Sale) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013
Available-for-sale Securities [Abstract]
Due within one year, Amortized Cost	$ 17,771
Due after one year through five years, Amortized Cost	158,054
Due after five years through ten years, Amortized Cost	244,429
Due after ten years, Amortized Cost	560,497
No stated maturity date, Amortized Cost Basis	3,324
Total investment securities available-for-sale, Amortized Cost	984,075
Due within one year, Fair Value	18,025
Due after one year through five years, Fair Value	161,996
Due after five years through ten years, Fair Value	249,097
Due after ten years, Fair Value	579,677
No stated maturity date, Fair Value	3,367
Total investment securities available-for-sale, Fair Value	$ 1,012,162