Investments (Amortized Cost and Estimated Fair Values of Investment Securities Available-For-Sale by Contractual Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Amortized Cost
Due in one year or less	$ 2,000	$ 2,080
Due after one year through five years	43,148	12,766
Due after five years through ten years	341,678	392,389
Due after ten years	293,176	342,732
Total debt securities available for sale	680,002	749,967
Estimated Fair Value
Due in one year or less	2,002	2,085
Due after one year through five years	44,500	13,285
Due after five years through ten years	348,934	392,339
Due after ten years	295,948	342,852
Total debt securities available for sale	$ 691,384	$ 750,561