Investments (Amortized Cost And Estimated Fair Value Of Debt Securities By Contractual Maturity) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Securities Available-for-Sale, Amortized Cost
Securities Available-for-Sale, Due in one year or less, Cost	$ 1,344
Securities Available-for-Sale, Due after one year through five years, Cost	14,996
Securities Available-for-Sale, Due after five years through ten years, Cost	185,615
Securities Available-for-Sale, Due after ten years, Cost	571,781
Securities Available-for-Sale, Cost, Total	773,736
Securities Available-for-Sale, Estimated Fair Value
Securities Available-for-Sale, Due in one year or less, Estimated Fair Value	1,355
Securities Available-for-Sale, Due after one year through five years, Estimated Fair Value	15,361
Securities Available-for-Sale, Due after five years through ten years, Estimated Fair Value	192,622
Securities Available-for-Sale, Due after ten years, Estimated Fair Value	587,102
Securities Available-for-Sale, Estimated Fair Value, Total	796,440
Securities Held-to-Maturity, Amortized Cost
Securities Held-to-Maturity, Due in one year or less, Cost	0
Securities Held-to-Maturity, Due after one year through five years, Cost	0
Securities Held-to-Maturity, Due after five years through ten years, Cost	4,934
Securities Held-to-Maturity, Due after ten years, Cost	46,277
Securities Held-to-Maturity, Amortized Cost	51,211	$ 60,827
Securities Held-to-Maturity, Estimated Fair Value
Securities Held-to-Maturity, Due in one year or less, Estimated Fair Value	0
Securities Held-to-Maturity, Due after one year through five years, Estimated Fair Value	0
Securities Held-to-Maturity, Due after five years through ten years, Estimated Fair Value	5,374
Securities Held-to-Maturity, Due after ten years, Estimated Fair Value	47,471
Securities Held-to-Maturity, Estimated Fair Value	$ 52,845	$ 60,706