Investments (Amortized Cost And Estimated Fair Value Of Debt Securities By Contractual Maturity) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Investments [Abstract]
Securities Available-for-Sale, Due in one year or less, Cost	$ 5,592
Securities Available-for-Sale, Due after one year through five years, Cost	24,793
Securities Available-for-Sale, Due after five years through ten years, Cost	132,761
Securities Available-for-Sale, Due after ten years, Cost	565,972
Securities Available-for-Sale, Cost, Total	729,118
Securities Available-for-Sale, Due in one year or less, Estimated Fair Value	5,572
Securities Available-for-Sale, Due after one year through five years, Estimated Fair Value	24,879
Securities Available-for-Sale, Due after five years through ten years, Estimated Fair Value	130,569
Securities Available-for-Sale, Due after ten years, Estimated Fair Value	557,041
Securities Available-for-Sale, Estimated Fair Value, Total	718,061
Securities Held-to-Maturity, Due after five years through ten years, Cost	4,927
Securities Held-to-Maturity, Due after ten years, Cost	55,900
Securities Held-to-Maturity, Cost, Total	60,827	$ 64,449
Securities Held-to-Maturity, Due after five years through ten years, Estimated Fair Value	5,053
Securities Held-to-Maturity, Due after ten years, Estimated Fair Value	55,653
Securities held-to-maturity, Estimated Fair Value	$ 60,706	$ 65,646