Securities (Schedule of Contractual Maturities of Investment Securities Available for Sale) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014
Available-for-sale Securities [Abstract]
Due within one year, Amortized Cost	$ 23,252
Due after one year through five years, Amortized Cost	337,507
Due after five years through ten years, Amortized Cost	434,217
Due after ten years, Amortized Cost	844,545
No stated maturity date, Amortized Cost Basis	5,284
Total investment securities available-for-sale, Amortized Cost	1,644,805
Due within one year, Fair Value	23,415
Due after one year through five years, Fair Value	336,477
Due after five years through ten years, Fair Value	431,506
Due after ten years, Fair Value	842,869
No stated maturity date, Fair Value	5,103
Total investment securities available-for-sale, Fair Value	$ 1,639,370